Canadian Journal of Gastroenterology and Hepatology

Canadian Journal of Gastroenterology and Hepatology / 2019 / Article

Review Article | Open Access

Volume 2019 |Article ID 3960920 | https://doi.org/10.1155/2019/3960920

Hsuan-An Su, Hsu-Heng Yen, Chih-Jung Chen, "An Update on Clinicopathological and Molecular Features of Plexiform Fibromyxoma", Canadian Journal of Gastroenterology and Hepatology, vol. 2019, Article ID 3960920, 26 pages, 2019. https://doi.org/10.1155/2019/3960920

An Update on Clinicopathological and Molecular Features of Plexiform Fibromyxoma

Academic Editor: Maikel P. Peppelenbosch
Received29 Apr 2019
Accepted16 Jun 2019
Published07 Jul 2019

Abstract

Plexiform fibromyxoma is a rare and newly described gastric mesenchymal tumor with only 121 reported cases in the literature. Our understanding of plexiform fibromyxoma requires updating since the first case has been reported by Takahashi et al. 12 years ago. The present review summarized reported cases in the literature, and both clinical and pathological aspects of plexiform fibromyxoma were comprehensively discussed. Plexiform fibromyxoma usually causes nonspecific or bleeding signs or symptoms, and therefore clinical recognition of the disease is challenging. Plexiform fibromyxoma is of benign nature without any metastasis or recurrence reported, and more conservative surgical treatment should be considered.

1. Introduction

Plexiform fibromyxoma (PF), also known as plexiform angiomyxoid myofibroblastic tumor (PAMT), was first described in 2007 by Takahashi et al. This rare tumor of mesenchymal origin is typically seen in the stomach and shows clinically benign behavior. As implied by the name, it features a plexiform cellular architecture of a myofibroblastic nature, encircled by a myxoid intercellular matrix with rich vasculature [1].

To date, only 121 cases have been reported in the literature with a designation of PF or PAMT; the clinical features of reported cases are summarized in Table 1. Specious case studies were published before the Takahashi’s first report in 2007, terming the condition “gastric fibromyxoma,” “gastric myxoma,” or “fibromyxoangioma” [28], but these are not included in the present review because the diagnoses could not be ascertained by immunohistochemical staining despite the similarity of the clinical features. Many cases have been reported since Takahashi first defined the entity 12 years ago; however, as new cases emerge, many facts about PF require updating, including the terminology, epidemiological data, various clinical presentations, diagnosis, diverse strategy on treatment, and prognosis. Correct updated information will help in the clinical recognition of the disease and improve the outcomes of treatments. The aim of this review is to provide a comprehensive updating of PF including the published cases to summarize what we know about PF, to identify what we still need to investigate, and to achieve consensus on all aspects of this disease. Hence, we present a review of the published cases in the literature and discuss clinically significant issues about PF.


NoYearAuthorPopulationAgeSexClinical PresentationUlcerLocationSize (cm)DiagnosisTreatmentPrognosis

1[1]2007TakahashiJapan50Macute abdominal pain (perforation)+pyloric antrum4 × 4 × 2.5PAMTdistal gastrectomyNA

2[1]2007TakahashiJapan68Mincidental-pyloric antrum4.5 × 3.5 × 3.0PAMTpartial gastrectomyuneventful for 12 months

3[17]2008GalantBelgium61Mhematemesiserosionantrum3.7PAMTpartial gastrectomyuneventful for 6 months

4[18]2008RauGermany50Fmorning nausea+antrum1.9 × 1.8 × 0.8PAMTMedian laparotomy and local excisionNo recurrence for 3 months

5[9]2008YoshidaUSA19Fmass in the stomach-antrum4.5 × 3.5 × 3.0PAMTdistal gastrectomyuneventful for 9 months

6[9]2008YoshidaUSA46Mupper gastrointestinal bleeding+antrum3.5PAMTdistal gastrectomyuneventful for 4 months

7[11]2009MiettinenUSA38Fupper gastrointestinal bleeding, ulcer+antrum, lesser curvature3 × 2PFdistal gastrectomylost f/u

8[11]2009MiettinenUSA62Mprogressive weight loss for months-antrum, pyloric4 × 4PFpartial gastrectomy, omentectomylost f/u

9[11]2009MiettinenUSA75Funknown+antrum, serosa5PFsubtotal gastrectomydied of unknown cause, 2 months

10[11]2009MiettinenUSA65Fweight loss, gastric ulcer+antrum, lesser curvature, duodenal bulb5 × 4.5 × 2.5PFpartial gastrectomydied of unknown cause, 14.5 years

11[11]2009MiettinenUSA33Manemia, weakness+antrum, anterior wall5.5 × 3.5 × 3.5PF50% distal gastrectomyalive without disease for 19.7 years

12[11]2009MiettinenUSA43Mgastrointestinal bleeding+antrum, near pylorus5.5 × 4.5 × 4.5PFpartial gastrectomyalive without disease for 18.4 years

13[11]2009MiettinenUSA56Funknown-pylorus, duodenal bulb5.5+3PFpartial gastrectomyalive without disease for 19.9 years

14[11]2009MiettinenUSA50Mgastric outlet obstruction-antrum, duodenal bulb7 × 6 × 6PFdistal gastrectomydied of unknown cause, 25.5 years

15[11]2009MiettinenUSA21Msyncope, anemia+antrum, prepyloric, duodenal bulb9 × 6 × 5PFantrectomy, B1-reconstructionalive with unknown status for 22 years

16[11]2009MiettinenUSA16Fhematemesis+antrum, pylorus10 × 9 × 6PFdistal gastrectomyalive with unknown status for 3 years

17[11]2009MiettinenUSA30Fnonhealing gastric ulcer+antrum10 × 9 × 6PFdistal gastrectomyalive without disease for 9 years, alive with unknown status for 24 years

18[11]2009MiettinenUSA7Femesis, diarrhea, protruding abdominal mass-antrum, pylorus, duodenal bulb15 × 11 × 8PFexcision of tumor, gastric wall resection at the tumor attachmentlost f/u

19[19]2009PailoorMalaysia23Fmelena+antrum8.0 × 4.0PAMTpartial gastrectomyuneventful for 2 months

20[20]2010SingSouth Africa (Indian)35Fcushingoid appearance, amenorrhea-pyloro-antral region, anterior wall of the greater curvature4 × 3 × 2PAMTexploratory laparotomy and wide local excisionuneventful for 12 months

21[10]2010TakahashiJapan23Mabdominal pain, abdominal discomfort, melena+antrum, duodenal bulb14 × 14 × 7PAMTpartial gastrectomyuneventful for 12 months

22[21]2010TanAustralia (Filipino)34Mabdominal mass, abdominal discomfort, decreased appetite (perforation)+antrum3.5 × 3.4 × 2.5PAMTdistal gastrectomyuneventful for 2 months

23[22]2010WangChina54Fabdominal distension, heartburn, hiccup, regurgitation, loss of appetiteerosionfundus1.5 × 1.2PAMTendoscopic resectionuneventful for 6 months

24[23]2010CooperUSA64Mepigastric painNAantrum4.0 × 2.0PAMTlaparoscopic excisionuneventful for 3 years

25[24]2010CuiChina54Fabdominal distension, decreased appetiteerosionfundus0.8PAMTNANA

26[14]2011KimKorea52Mdyspepsia+antrum3.5 × 2.3PAMTlaparoscopic wedge resectionuneventful for 5 months

27[25]2012KangKorea47Mincidental+mid body, posterior wall and greater curvature3 × 2PAMTwedge resectionuneventful for 6 years

28[25]2012KangKorea63Fincidental+lower body, greater curvature2.2 × 1.6PAMTendoscopic resectionuneventful for 1 month

29[26]2012SchulzGermany59Mheartburn, upper abdominal pain+pylorus1.5PAMTcombined laparoscopic endoscopic local resectionNA

30[27]2012CaiChina32MincidentalNAantrumPFdistal gastrectomyNA

31[27]2012CaiChina47Fupper abdominal painNAantrumPFradical distal gastrectomyNA

32[28]2012WangChina12Mgastrointestinal bleedingNAantrumPFpartial gastrectomyuneventful for 84 months

33[29]2012MiettinenUSA49FNANAantrum3.5 × 2.5 × 2.5PFwedge resectionNA

34[30]2012LiChina47Fepigastric discomfort, abdominal pain-antrum5 × 3 × 2PAMTlaparoscopic distal gastrectomyuneventful for 1.5 years

35[31]2012BiChina31MAbdominal pain-Antrum8.0PAMTNANA

36[31]2012BiChina47FAbdominal pain+Antrum4.5PAMTNANA

37[31]2012BiChina42FAbdominal distension-Antrum4.6PAMTNANA

38[32]2013KaoChina53FAbdominal distension, abdominal pain, nausea, acid regurgitationNANANAPAMTNANA

39[33]2014BaekKorea38Fincidental+upper body, posterior wall and greater curvature3.5 × 2.3PAMTwedge resectionuneventful for 6 months

40[34]2014DuckworthUSA16Fchest pain, shortness of breath, finger numbnessNAposterior mediastinum near the esophagus at the level of the carina3.2PFthoracoscopic resectionuneventful for 14 months

41[34]2014DuckworthUSA11Fsevere iron-deficiency anemia+pylorus3.5PFlaparoscopic distal gastrectomyuneventful for 15 months

42[35]2014IkemuraJapan27Fepigastric pain, melena, anemia+antrum of the lesser curvature side4.6 × 3.0 × 2.8PAMTpartial gastrectomyuneventful for 40 months

43[36]2014LeeHong Kong (Filipino)42Fabdominal pain, fever, anemia (fistulating abscess formation)+antrum12.9 × 11.9 × 10.6PFdistal gastrectomyuneventful for 3 weeks

44[37]2014LiChinese32Mincidental-antrum, anterior wall3.4 × 3.0PAMTpartial gastrectomyuneventful for 3 years

45[38]2014SakamotoJapan60Mepigastralgia+antrum2PFlaparoscopic partial gastrectomyuneventful for 12 years

46[39]2014LiChina73Fupper abdominal painNAantrumPFpartial gastrectomyNA

47[40]2014TianChina64Mupper abdominal discomfort-antrum3.3 × 2.5PFdistal gastrectomyuneventful for 6 months

48[41]2015BanerjeeIndia19Fdull upper abdominal pain, lump in the right hypochondrium+duodenum (D1), posterior13.8 × 8.6PAMTdistal gastrectomy, proximal duodenectomy, Billroth II gastrojejunostomyuneventful for 6 months

49[42]2015FassanItaly (Caucasian)55FcholelithiasisNAgallbladder1PFlaparoscopic cholecystectomyno postsurgical complication

50[43]2015LuChina26Fprogressive abdominal distension, nausea, vomiting, melenaNAantrumNAPAMTdistal gastrectomyNA

51[44]2015NiChina21Fmelena, dizziness, anemia+antrum, greater curvature4 × 3 × 3PFdistal gastrectomyuneventful for 3 years

52[45]2015WeiChina50Fupper abdominal painNAantrumPFsubtotal gastrectomyuneventful for 3 months

53[46]2015YueChina34Mupper abdominal painNAantrumPFdistal gastrectomyuneventful for 24 months

54[46]2015YueChina50Fupper abdominal painNAantrumPFsubtotal gastrectomyuneventful for 3 months

55[47]2015XuChina50Fabdominal painNAgastric body3 × 2PAMTTotal gastrectomyuneventful for 6 months

56[15]2016DixitIndia51Fabdominal pain, vomiting, weight loss (with synchronous ovarian neoplasms)+pylorus8.4 × 6.1 × 5PAMTdistal gastrectomyno postsurgical complication

57[48]2016InoueJapan36Fepigastric pain, anemia+antrum2.5 × 2.2 × 2.0PFradical resection with laparoscopic endoscopic cooperative surgeryuneventful for unknown period

58[49]2016JonaitisLithuania (Caucasian)28Fepigastric pain associated with meals, iron-deficiency anemia, weight loss+antrum, anterior wall3PAMTpartial gastrectomy of the Billroth I typefollow-up not reported; gastroduodenal anastomositis, resolved with conservative treatment

59[50]2016KaneUSA (Vietnamese)28Facute, severe abdominal pain and worsening anemia+antrum5.5 × 3.5PFdistal gastrectomy with a Roux-en-Y gastrojejunostomydyspepsia 23 months thereafter, otherwise uneventful for 23 months (only moderate stenosis of anastomosis)

60[51]2016MorrisUSA9Fintermittent abdominal pain, nausea, vomiting, weight loss+antrum, posterior5PFlaparotomic anterior gastrotomy with tumor resectionuneventful for 6 months

61[52]2016NagahisaJapan39Mepigastric pain+antrum, anterior wall3.5 × 3PAMTpartial gastrectomy with laparoscopic endoscopic cooperative surgeryuneventful for 9 months

62[53]2016QueroItaly47Msyncope, regurgitation, epigastric discomfort+antrum6.5PAMTdistal gastrectomyuneventful for 10 months

63[54]2016SpansBelgium19MNANAantrum5.5PFNANA

64[54]2016SpansBelgium65FNANAantrum4.3 × 3.0 × 1.7PFNANA

65[54]2016SpansBelgium58FNANAantrumNAPFNANA

66[54]2016SpansBelgium51FNANAantrum9.0 × 8.5 × 5.5PFNANA

67[54]2016SpansBelgium63FNANAjejunum, proximal3.5 × 3.0 × 2.0PFNANA

68[54]2016SpansBelgium76FNANAstomach4PFNANA

69[54]2016SpansBelgium62FNANAstomachNAPFNANA

70[54]2016SpansBelgium30FNANAstomach2PFNANA

71[54]2016SpansBelgium28MNANAgastric body10 × 6 × 3PFNANA

72[54]2016SpansBelgium44FNANAstomachNAPFNANA

73[54]2016SpansBelgium18FNANAantrum4.5 × 3.5 × 2.7PFNANA

74[54]2016SpansBelgium19FNANAstomach4.5PFNANA

75[54]2016SpansBelgium46MNANAantrum3.5PFNANA

76[54]2016SpansBelgium29MNANAantrum6.5 × 4.5 × 4.0PFNANA

77[54]2016SpansBelgium36FNANAantrum8PFNANA

78[54]2016SpansBelgium47FNANAantrum4.5 × 3.7PFNANA

79[55]2016LiChina11Mupper abdominal discomfortNAantrumPFpartial gastrectomyuneventful for 12 months

80[56]2016LiChinese44Fincidental-antrum0.8 × 0.8PAMTendoscopic submucosal dissectionuneventful for 6 months

81[57]2016ZhangChina48Mupper abdominal painNAantrumPFpartial gastrectomyuneventful for 12 months

82[16]2017AkaiJapan55MincidentalNAgastric angle1.7PAMTlaparoscopic partial gastrectomyNA

83[58]2017Gonzalez-CorderoSpain37Mupper gastrointestinal bleeding with hemodynamic instabilityNAantrum5.8 × 5 × 4PFantrectomyuneventful postoperatively

84[59]2017HuChina26Mabdominal distension+fundus1.8PFendoscopic submucosal dissectionuneventful for 32 months

85[59]2017HuChina31Fabdominal distension-antrum2.5PFendoscopic submucosal dissectionNA

86[59]2017HuChina72Fabdominal distension+antrum7PFdistal subtotal gastrectomyuneventful for 56 months

87[59]2017HuChina59Fabdominal distension+antrum2.5PFdistal subtotal gastrectomyuneventful for 68 months

88[59]2017HuChina52Mincidental+fundus1.2PFendoscopic submucosal dissectionuneventful for 24 months

89[59]2017HuChina59Fmelena, anemia+antrum3PFdistal subtotal gastrectomyuneventful for 40 months

90[59]2017HuChina48Mabdominal distension+antrum3PFdistal subtotal gastrectomyuneventful for 95 months

91[59]2017HuChina58Mabdominal pain+antrum3.5PFdistal subtotal gastrectomyuneventful for 34 months

92[59]2017HuChina46Mabdominal distension-antrum4PFdistal subtotal gastrectomyuneventful for 65 months

93[59]2017HuChina40Fmelena, anemia+antrum3.8PFdistal subtotal gastrectomyuneventful for 70 months

94[60]2017KawaraJapan66Mgastric tumor-antrum4 × 3PFendoscopic submucosal dissectionuneventful for 12 months

95[61]2017KimKorea51Mincidental-antrum, lesser curvature2.0 × 1.5PAMTlaparoscopic gastric wedge resectionuneventful for 3 years

96[62]2017LiangChina11Mright epigastric discomfort with episodic pain-pylorus, anterior17 × 10.5 × 5PAMTpartial gastrectomyuneventful for 12 months

97[63]2017MorisUSA63Mupper gastrointestinal bleeding, anemia, melenaNAduodenum3 × 3PFpancreas-preserving duodenectomy of the first 2 portionsuneventful for 20 months, complicated only by a low output pancreatic skin fistula totally drained after 4 months

98[64]2017QiChina42Mmelena+antrum, greater curvature3 × 2 × 1.8PFlaparoscopic partial gastrectomyuneventful for 12 months

99[64]2017QiChina66Mepigastric pain-antrum, greater curvature2 × 1 × 0.7PFendoscopic submucosal dissectionuneventful for 12 months

100[65]2017SzurianAustria (Caucasian)16Fanemia, nausea+antrum, anterior wall6.5PFdistal gastrectomy and retrocolic gastrojejunostomy (Billroth II)pulmonary embolism postoperatively and discharged on day 9, otherwise uneventful for 6 months

101[65]2017SzurianAustria34Mepigastric discomfort, flatulence+pylorus1.6PFdistal gastrectomy and retrocolic gastrojejunostomy (Billroth II)uneventful for 16 months

102[66]2017WamburaTanzania (Tanzanian)41Fanemia, epigastric discomfort, melena+antrum5.5 × 5PFdistal gastrectomy with Roux-en-Y gastrojejunostomyuneventful for 12 months

103[67]2017YangChina50Fabdominal pain-gastric upper body15 × 10PFlaparoscopic partial gastrectomyuneventful for 2 years

104[68]2017ZhouChina51Mepigastric discomfort, heartburnNAantrum, greater curvature4 × 3 × 1.8PFtotal resectionuneventful for 15 months

105[69]2017WangChina66FAbdominal pain, melena, dizziness, abdominal distensionerosionAntrum3PFNANA

106[70]2018DjurićSerbia14Miron-deficiency anemia, fatigue, epigastric painNAAntrumNAPFpartial gastrectomyNA

107[71]2018JangKorea47Fheartburn-pylorus2.5 × 2.0PFantrectomy with Billroth I anastomosisuneventful for 7 months

108[72]2018RohitUSA81Fweight loss of 3.6 kg in 3 monthsNAgastric body, lesser curvature2.7 × 2.4PFnon-surgical follow-upsymptom resolved 3 months after

109[73]2018WangChinese52Fupper abdominal pain+mid gastric body, greater curvature1.5 × 1.0 × 1.0PFgastroscope-assisted laparoscopic wedge resectionuneventful for 10 months

110[74]2018ZhangChina31Fhematochezia, syncope, upper gastrointestinal bleeding, anemia+upper segment of jejunum1.2 × 1.0PFexploratory laparotomy and resection of the upper jejunal tumor and local intestineuneventful for 3 years

1112019WuTaiwan (Taiwanese)59Facid regurgitation-antrum2 × 1.2 × 1.2PFpartial gastrectomyuneventful for 20 months

112[75]2019FukazawaJapan14Fabdominal pain, hematemesis+antrumPFpartial gastrectomyuneventful for 16 months

113[76]2019BanerjeeUSA65Manemia, early satiety, dyspepsia, hematemesis+antrum5 × 2.3PFwedge resectionNA

114[77]2019LaiUSA21FNANAgastric bodyPFpartial gastrectomy4 years

115[77]2019LaiUSA42FNA+antrumPFpartial gastrectomy4 years

116[77]2019LaiUSA79FNANAantrumPFpartial gastrectomy1 year

117[77]2019LaiUSA33MNANAantrumPFpartial gastrectomy11 years

118[77]2019LaiUSA60MNANAantrumPFpartial gastrectomy1 year

119[77]2019LaiUSA77MNANAgastric bodyPFpartial gastrectomy2 years

120[77]2019LaiUSA45MNANAantrumPFonly endoscopic biopsy0.2 years

121[78]2019LiChina5Mpale complexionNAantrum8.2 × 7.5 × 5.5PFdistal gastrectomy36 months

2. History and Nomenclature

Takahashi et al., in 2007, reported 2 cases of gastric plexiform fibromyxoma using the term “plexiform angiomyxoid myofibroblastic tumor (PAMT)” because the condition was morphologically distinct from other gastrointestinal mesenchymal tumors due to its bland spindle cells in a plexiform pattern, myxoid intercellular matrix with hypervascularity, and myofibroblastic nature [1]. In 2008, Yoshida et al. reported 2 additional cases and modified the designation to “plexiform angiomyxoid tumor,” deleting the term “myofibroblastic” due to the evident differentiation into smooth muscle cells that had been absent from the previous report and emphasizing the differentiating potential of myofibroblasts into smooth muscle cells. Yoshida et al. also further characterized the spectrum of fibrous, fibromyxoid, and myxoid stromal patterns of the disease [9]. Takahashi et al. continued to use the designation “myofibroblastic,” because this presentation was seen in the majority of cases [10].

In 2009, Miettinen et al. described 12 cases of the disease and designated the tumors as “plexiform fibromyxoma” simply due to their cellular architecture and fibromyxoid nature [11]. They also identified previously reported diseases from 1959 to 1986 that shared similar characteristics with PF by the names “gastric fibromyxoma” or “gastric myxoma” [2, 5, 6, 8, 12]. In 2010, Takahashi et al. argued that the designation “plexiform fibromyxoma” could lead to confusion, since “gastric fibromyxoma” or “gastric myxoma” describes a relatively narrow entity of purely fibroblastic tumors that present a different immunoprofile from that of PAMT; consequently, those cases reported as “gastric fibromyxoma” or “gastric myxoma” might actually differ from PAMT and would require further pathological or immunological evidence [10]. However, the WHO classification of tumors of the digestive system later adopted the term “plexiform fibromyxoma” in 2010 to designate the entity [13]. Since then, both “plexiform fibromyxoma” and “plexiform angiomyxoid myofibroblastic tumor” have both been used as the nomenclature of the disease, with controversy in the literature. Despite the nomenclature set by the WHO classification, many authors still preferred the term PAMT as a better description of both the histogenesis and histology of the tumor [1416]. In the present review, 85 cases were designated as PF, while 36 were designated as PAMT.

Sing et al. proposed that PF and PAMT are two related, but different, entities at two respective fibroblastic and myofibroblastic ends of a spectrum [20]. Yet, due to the generally close similarity of the two, Duckworth et al. considered the two to be a single entity with an acceptable range of histologic, immunohistochemical, and ultrastructural presentations [34]. By contrast, Sing et al. argued that PF occupies the “fibroblastic” end while PAMT occupies the fully differentiated “myofibroblastic” end of the spectrum, and that the size, female exclusiveness of PF, vascular invasion, and extragastric extension are distinguishable between the two, despite the similar location of occurrence and age of onset [20]. Immunohistochemically, Sing et al. suggested that desmin and caldesmon could be used to distinguish PAMT as it shows focally positive results, whereas PF shows negative results. However, on the grounds of the limited case numbers for PF and PAMT and that desmin and caldesmon were not specific for the myofibroblastic form only, we suggest that discrimination of the two designations is unnecessary. In the literature, the cases designated as PF and those as PAMT showed no significant difference in age of onset or mean tumor size and both had female predominance and extragastric involvement. Although vascular invasion had only been reported in PF cases, the number of cases with vascular invasion is very small.

Since the WHO classification had designated the nomenclature PF for this entity, to avoid confusion in the literature, we suggest the use of PF in consideration of epidemiological surveillance and scientific communication purposes. The term PAMT literally describes the features of the disease in more detail, but PF could be viewed sensu lato as a broader nomenclature that covers the disease as well as other variants. We consider this to be acceptable, given that the disease is a spectrum with variations. The final designation or subsets under PF could be further categorized in the future after consideration of sufficient case numbers and advanced investigations.

3. Epidemiology

According to the 110 cases reported in the literature from 2007 to 2018, the frequency of PF is more than 9.17 cases per year worldwide. However, we feel this is an underestimate, because clinical recognition of the disease has only been increasing since 2007, and some cases are assumed to have been misidentified as gastrointestinal stromal tumors (GISTs) or other entities. Miettinen et al. estimated that the frequency of PF is 150 times lower than gastric GIST [11]; however, about 3,000 cases of gastric GIST are diagnosed yearly in the United States [79]. Therefore, we consider a proportion of 1:150 to be a rather conservative estimation and should be far smaller.

The patient ages showed a broad range, from 5 to 81 years (mean age 43.17±18.00 years; median age 46 years). Most patients were middle-aged, with a peak around 30–60 years old. This age distribution of PF was in approximate accordance with previous reviews [10, 51]; however, the adult-to-child ratio was 8:1 by our estimation, unlike the 5:1 ratio stated by Morris’s [51] but more similar to the 7:1 ratio proposed by Fukuzawa’s in a recent systematic review [75]. The previous studies all reported a 1:1 male-female ratio for PF [10, 51, 59], although we found a slight female predominance, with male patients accounting for 43% and female patients for 57%.

The races of patients were not provided in most of the studies; consequently, the countries of the studies were substituted for the ethnicity of the patients unless the ethnic information of the patients was given. In terms of regions, most cases were reported from East Asia (N=58; 47.9%), followed by North America (N=29; 24.0%), Europe (N=26; 21.5%), South-East Asia (N=4; 3.3%), South Asia (N=3; 2.5%), and Africa (N=1, 0.8%). In terms of countries, most cases were reported from China (N=41; 33.9%), followed by the United States (N=29; 24.0%), Belgium (N=17; 14.0%), Japan (N=10; 8.3%), and Korea (N=6; 5.0%). This distribution may not reflect the genuine epidemiological status of PF, since a higher frequency may result from a higher quality of healthcare and from a larger population. Nevertheless, it still suggests that PF is a worldwide disease with a predominance in East Asia.

4. Clinical Presentation

PF has a benign nature but is associated with hypervascularity; therefore, the clinical presentation can range from incidental findings to nonspecific gastrointestinal (GI) symptoms and further to severe GI hemorrhage. The typical presentation of PF is a nonspecific gastrointestinal complaint, such as abdominal pain, abdominal distension, and abdominal discomfort. Hemorrhagic gastrointestinal presentations are also commonly seen, with consequent GI bleeding-associated presentations like anemia, melena, and hematemesis [10, 36, 68, 74]. The available literature includes 121 cases, with clinical signs and symptoms available for 95 cases. The clinical presentations listed in Table 2 could be sorted into 3 categories, including abdominal signs or symptoms, bleeding signs or symptoms, and others. Most clinical presentations were abdominal signs or symptoms, mostly nonspecific, such as abdominal pain, abdominal distension, abdominal discomfort, abdominal mass, nausea, and heartburn. Many patients also presented with bleeding signs or symptoms, including anemia, melena, GI bleeding, and hematemesis. Severe hemorrhage leading to syncope [11, 53, 74] or hemodynamic instability [58] was also reported. Reflux symptoms might be present, with or without other complaints, and are likely to mask PF if presenting alone or with nonspecific complaints [22, 26, 68, 71, 80]. Among the cases that presented with reflux symptoms, only one tumor was located at the gastric fundus and might have been the cause of the symptoms [22]; other tumors were located at the gastric pylorus or antrum [26, 53, 68, 71, 80]. The likelihood that PF could directly or indirectly provoke reflux symptoms is doubtful, and the reflux symptoms were more likely to be concurrent with PF because of the high GERD prevalence worldwide. Ten cases were diagnosed incidentally, even with ulcerative PF lesions [25, 33, 59]; the size of incidentally diagnosed tumor ranged from 0.8 to 4.5 cm, and 4 tumors were located at gastric body, 1 was located at gastric fundus, and 5 were located at gastric antrum or pylorus [1, 16, 25, 27, 33, 37, 56, 59, 61]. Two cases with hemorrhagic perforation were reported by Takahashi et al. and Tan et al., with maximal tumor diameters of 4 and 3.5 cm, respectively [1, 21]. Other signs or symptoms at presentation included amenorrhea with cushingoid appearance in a 35-year-old female, but her symptoms were actually caused by polycystic ovary syndrome [20]. Chest pain with shortness of breath and finger numbness in a 16-year-old female was probably a result of a mass effect of the 3.2 cm PF in the mediastinum [34], while cholelithiasis was reported in a 55-year-old female with a PF in the gallbladder [42]. Fever was reported in a 42-year-old female with a fistulating abscess formation connecting the tumor and gastric lumen, suggesting possible infection sequelae of PF if left untreated [36]. The pathogenic association between these signs or symptoms and PF could not be proven; however, physicians are reminded of the nonspecific presentation of the disease. If a gastric neoplasm is clinically suspected, further endoscopic diagnostic intervention is indicated.


Clinical PresentationCountPercentage (%)

Abdominal Signs or Symptoms

Abdominal pain3320.6
Abdominal distension138.1
Abdominal discomfort106.3
Abdominal mass53.1
Nausea53.1
Heartburning sensation42.5
Acid regurgitation42.5
Vomiting42.5
Decreased appetite31.9
Dyspepsia21.3
Diarrhea10.6
Early satiety10.6
Gastric outlet obstruction10.6
Hiccup10.6

Bleeding Signs or Symptoms

Anemia1811.3
Melena116.9
Gastrointestinal bleeding74.4
Hematemesis42.5
Syncope31.9
Dizziness21.3
Gastric ulcer21.3
Fatigue10.6
Hematochezia10.6

Others

Incidental106.3
Weight loss74.4
Amenorrhea10.6
Chest pain10.6
Cholelithiasis10.6
Cushingoid appearance10.6
Fever10.6
Finger numbness10.6
Shortness of breath10.6

5. Location

Although initially categorized as a gastrointestinal mesenchymal tumor [1], PF has been reported to occur at locations other than in the gastrointestinal tract. The locations of the tumors were reported in 120 cases. Most of the tumor locations were the gastric antrum (including pylorus and gastric angle, N=95; 79.2%), followed, in decreasing order, by gastric body (N=10; 8.3%), stomach (inside location unspecified, N=5; 4.2%), gastric fundus (N=4; 3.3%), duodenum (N=2; 1.7%), jejunum (N=2; 1.7%), gallbladder (N=1; 0.8%), and mediastinum (N=1; 0.8%). The tumors often involve the pylorus and extended into the duodenal bulbs, probably causing obstruction [10, 11, 71]. Therefore, despite its gastric predominance, PF does not exclusively occur in the stomach and is also not confined to the GI tract, as indicated by 114 gastric tumors and 6 extragastric tumors.

6. Endoscopic Findings/Macroscopic Pathological Findings

The size of the tumors, available in 98 cases, ranged from 0.8 to 17 cm in the maximal diameter, with an average size of 4.81±3.30 cm and a median size of 4.0 cm. Endoscopic visualization reveals that PFs are typically pink or reddish and glistening tumors, elastic in texture, and covered with ulcerative, erosive, or smooth mucosa. Endoscopic ultrasonography indicates that PFs are hypoechoic with mild heterogenicity. Macroscopic examination shows a classical PF appearance as a lobulated tan-white or grayish-whitish mass, gelatinous on the cut surface, cystic, with mucinous fluids, a multinodular or polypoidal growth pattern, unencapsulated, and with well-defined (but sometimes ill-defined) margins. Hemorrhage is commonly encountered. PFs mostly originate from the submucosa and muscularis propria, with extension ranging from the mucosa to the serosa, causing ulcer and/or perforation.

The condition of the tumor surface was reported in 76 cases: 50 (65.8%) were ulcerated, 22 (28.9%) were nonulcerated, and 4 (5.3%) were covered with eroded mucosa. Ulceration or erosion of the tumor was significantly associated with hemorrhage-related signs or symptoms, as determined by Pearson’s chi-squared test (p<0.0001). The difference in tumor size between ulcerative or erosive lesions and nonulcerative lesions was not statistically significant, as calculated by an independent Student’s t-test (p=0.184).

7. Microscopic Findings

The signature of PF, as disclosed in the name PAMT, is the presence of bland ovoid to spindle cells arranged in irregular plexiform or multinodular pattern and separated by abundant myxoid and a variably collagenized extracellular background, interwoven with rich, arborizing, capillary-sized vasculature. The myxoid matrix is consistently Alcian blue positive. The tumor cells demonstrate monomorphous oval nuclei containing indistinct nucleoli and fine chromatin, surrounded by mildly eosinophilic cytoplasm with indistinct borders. Delicate and indistinct nucleoli and fine chromatin may be present. Cellular atypia and mitosis are both rare and are not seen in the majority of the cases. Microscopically, the tumor margin is infiltrative and unencapsulated; in 33 cases reporting the condition tumor margin, 20 were ill-defined and the rest were well-circumscribed. Necrosis was reported in the literature in only 2 cases: a 42-year-old female with fistulating abscess showed central necrosis as well as gas-fluids level [36], and a 31-year-old female with an ulcerative lesion exhibited only surface necrotic tissue coverage without central necrosis [74]. Some lymph nodes display enlargement with reactive changes [19, 67]. Vascular or lymphatic involvement was observed in 5 cases [11, 60].

In all, 118 cases reported immunohistochemical profiles of the tumor with various markers (Table 3). Immunohistochemical staining in most cases showed positive results for vimentin, smooth muscle actin (SMA), and muscle specific actin (MSA), indicating the fibroblastic, myofibroblastic, and smooth muscle cell natures of PF. Negative results for DOG-1, CD117 (KIT), CD34, S-100 protein, neurofilament, cytokeratin, epithelial membrane antigen (EMA), and ALK suggest that PF is a distinct disease entity from GIST, angiomyxoma, neurogenic tumor, sarcomatoid carcinoma, and inflammatory myofibroblastic tumor. Partial immunoreactive or focally positive results with desmin, caldesmon, and CD10, consistent with a partial or incomplete muscle immunophenotype, suggest possible myofibroblastic differentiation. Ki-67 staining commonly illustrates very low proliferation rates, mostly <2%, indicating a very low grade/indolent mesenchymal tumor; nevertheless, 5% [44, 74], 6% [25], 30% [77], and a vascular endothelial Ki-67 index up to 40% [49] have also been reported.


NoYearAuthorAgeSexKi-67VimSMAMSADOG-1CD117CD34DesminCaldS-100 proteinCalpEMANFCKERPRCD10β-CALKAE1/AE3SNPC-KITPDFGRA

12007Takahashi50M<1%+++---+/-------

22007Takahashi68M<1%+++---+/-------

32008Galant61M++-----

42008Rau50F2%++-+/- (focal)+/- (sporadic)-----

52008Yoshida19F---------

62008Yoshida46M<1%++--+/- (focal)+ (partial)-+ (partial)---

72009Miettinen38F+ (8/10)----- (3/3)-+ (1/3), -(2/3)- (3/3)wt (3/3)wt (3/3)
82009Miettinen62M-----
92009Miettinen75F-----
102009Miettinen65F-----
112009Miettinen33M-----
122009Miettinen43M-----
132009Miettinen56F-----
142009Miettinen50M-----
152009Miettinen21M-----
162009Miettinen16F-----
172009Miettinen30F-----
182009Miettinen7F-----

192009Pailoor23F++--+/- (partial)-

202010Sing35F+++--++-+-+----

212010Takahashi23M++---------

222010Tan34M<2%+--+---

232010Wang54F<1%++---

242010Cooper64M++------

252011Kim52M+-+/- (partial)-

262012Kang47M6%+------

272012Kang63F+-----wtwt

282012Schulz59M<2%+--------

292012Cai32M++---

302012Cai47F++---

312012Wang12M++----

322012Miettinen49F++-+ (variably)

332012Li47F<1%+------

342012Bi31M+++

352012Bi47F++

362012Bi42F++++++

372014Baek38F+---

382014Duckworth16F1% (focally 8%)+-----

392014Duckworth11F++--+-+---

402014Ikemura27FSmall Percentage+--+/- (partial)--+

412014Lee42F++------

422014Li32M<1%++/- (partial)---+ (partial)+ (partial)---

432014Sakamoto60M------

442014Li73F++---

452014Tian64M+---

462015Banerjee19F---------

472015Fassan55F0%+++-+------

482015Lu26F++---

492015Ni21F5%++-----

502015Wei50F+--

512015Yue34M++----

522015Yue50F++----

532015Xu50F<1%++-----

542016Dixit51F<1%+------

552016Inoue36F

562016Jonaitis28F40% (vascular endothelial Ki-67)+---

572016Kane28F+----+/- (focal)--

582016Morris9F+---+/- (focal)-+-+/- (focal)-

592016Nagahisa39M+---

602016Quero47M++---+/- (partial)+/- (partial)--+/- (partial)-+/- (focal)-wtwt

612016Spans19M+-----

622016Spans65F+------

632016Spans58F+------

642016Spans51F++/- (focal)-

652016Spans63F++/- (focal)-

662016Spans76F+/- (focal)+

672016Spans62F+/- (focal)-

682016Spans30F++

692016Spans28M+-+/- (focal)+-

702016Spans44F+/- (focal)+-

712016Spans18F+/- (focal)+/- (focal)

722016Spans19F+-----

732016Spans46M+---

742016Spans29M+-----

752016Spans36F+----

762016Spans47F+----

772016Li11M+--+

782016Zhang48M++----

792016Li44F+--+--

802017Akai55M+--+--

812017Gonzalez-Cordero37M+---+-+-

822017Hu26M++--+/- (negative/focal)+/- (patchy, 5/10)+/- (patchy, 6/10)--+ (patchy/ diffusely at nucleus, 6/10)+ (patchy, 5/10)-wt (5/10)wt (5/10)
832017Hu31F++-----
842017Hu72F++-----
852017Hu59F++-----
862017Hu52M++-----
872017Hu59F++-----
882017Hu48M++-----
892017Hu58M++-----
902017Hu46M++-----
912017Hu40F++-----

922017Kawara66M2%+ (focal)+ (focal)------+ (focal)-

932017Kim51M+-

942017Liang11M+ (focal)----+ (focal)-+ (focal)-

952017Moris63M+-----wtwt

962017Qi42M1%++---+ (partial)+ (partial)-+ (partial)---

972017Qi66M1%++-------

982017Szurian16F+---+ (focal)+ (focal)-+/- (focal)----

992017Szurian34M+------+/- (focal)--

1002017Wambura41F+-----

1012017Yang50F3%++--+-------

1022017Zhou51M1%+--------

1032018Djurić14M+---+ (focal)---

1042018Jang47F+---+ (focal)--+ (focal)

1052018Rohit81F+ (patchy)------

1062018Wang52F1%+----+-+

1072018Zhang31F<5%+-------+ (partial)

1082019Wu59F+---+/- (focal)----

1092019Fukazawa14F2%++------

1102019Banerjee65M+----

1112019Lai21F+----

1122019Lai42F-----

1132019Lai79F30%+---+/- (focal)-

1142019Lai33M+--+/- (focal)-

1152019Lai60M+---+ (focal)-

1162019Lai77M+---

1172019Lai45M+---

1182019Li5M++------

Abbreviations: Dx, diagnosis; Vim, vimentin; Cald, caldesmon; Calp, calponin; NF, neurofilament; CK, cytokeratin; β-C, β-catenin; SNP, synaptophysin; wt, wild type.

Significantly or diffusely reactive immunostainings included vimentin (100%), SMA (89.1%), and MSA (90%); however, these are nonspecific markers for mesenchymal and myofibroblastic lineages and were therefore sensitive but specific for diagnosing PF. Equivocal staining results were demonstrated for desmin, caldesmon, calponin, CD10, estrogen receptor (ER), and progesterone receptor (PR). Desmin and caldesmon are more specific markers for muscular lineage toward terminal muscle cell differentiation and exhibited limited and focal reactive results in PF, consistent with the proposed myofibroblastic spectrum of PF cell development.

Calponin is a nonspecific muscular marker for differentiated smooth muscle cells, while CD10 indicates cells with fibroblastic traits. The calponin and CD10 results confirmed the variably myofibroblastic nature of PF in the muscular and fibroblastic axes, respectively. The ER showed all negative staining, but the PR were diffusely or focally reactive in 8 of 10 cases [20, 31, 59], one of which revealed a prominent PR positivity in 80% of the tumor cells [20]. The PR positivity implied that PF may be sensitive to hormonal therapy [20, 59], but this might not be clinically practical. PF is reminiscent of extra-uterine or metastatic endometrial stromal sarcoma, which is rare but most commonly occurs in the GI tract [20]. However, it typically presents ER positivity [81], while PF consistently shows negative ER immunostaining result.

The rest of the markers mainly had negative results in PF. DOG-1 and CD117 were always negative in the reported cases, which allowed PF to be well-distinguished from GIST [82]. CD34 was mostly negative (95.1%), but focally positive results have been shown in several cases. CD34 could be labeled in cells with fibroblastic nature [83], but CD34 shows strong positive staining in vascular endothelial tissues; therefore, we suggest the possibility that focally positive or equivocal results originate from the rich vascularity of PF or as a result of technical or interpretation errors. The PF cases showed almost entirely negative results according to S-100 protein staining, indicating that PF is not derived from the neural crest; the 2 cases reporting positive results we highly suspect to be biased by technical error. Except for 1 case with a positive EMA staining result and 1 case with focally positive cytokeratin AE1/AE3 staining result, negative outcomes were reported for EMA, neurofilament, cytokeratin, β-catenin, ALK, cytokeratin AE1/AE3, and synaptophysin, thereby excluding epithelial, perineural, neuronal, and neuroendocrine cell lineage and ruling out some of the important differential diagnoses, such as fibromatosis and inflammatory myofibroblastic tumor.

Genetic mutation has also been examined in some studies. The C-KIT and PDGFRA gene mutations are important and characteristic in GIST [82], but they were both negative in all PF cases reported, thereby further enhancing the differentiation between PF and GIST. Genetic mutations involving glioma-associated oncogene homologue 1 (GLI1) and metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) have been identified in a subset of PF cases [54, 59], with GLI1 gene translocation reported in 6 cases (24%) and GLI1 polysomy reported in 2 cases (8%), out of overall 25 cases with GLI1 genetic analysis [54, 59, 78]. The gene translocation t(11;12)(q11;q13) producing functional MALAT1-GLI1 chimeric proteins and the polysomy of GLI1/12q13 both will lead to overexpression of GLI1 protein. The overproduction of GLI1 protein has been recognized in a wide range of neoplasms [84, 85] and occurs via activation of the Hedgehog signaling pathway [54], which plays important roles in gastrointestinal developments, diseases, and neoplasms [86]. Apart from the canonical pathway of Hedgehog signaling, a noncanonical, Patched-dependent, and Smoothened-independent pathway has been recently described, which may be vital for the maintenance of gastrointestinal neoplasms [87]. The molecular pathway of PF development implicates that such neoplasms with GLI1 oncogenesis may be sensitive to Hedgehog pathway inhibitors, targeting either Patched, Smoothened, GLI1, or other Hedgehog pathway components [88]. PF remains an emerging disease entity, and we are far from understanding its genetic profile with such a limited case number. Nevertheless, the present results of genetic analysis that aimed at benefiting differential diagnosis confirm a different genetic profile from GIST, and further research on the GLI1 mutation and Hedgehog signaling may bring about improved understanding of its pathogenesis and even novel therapeutic strategies.

8. Diagnosis and Differential Diagnoses

Clinical findings are indecisive for the diagnosis of PF, as a solid, elastic tumor with or without ulceration is most likely to be encountered first during endoscopy, with typically nonspecific or hemorrhagic gastrointestinal signs or symptoms. Diagnosis of PF depends on pathological and immunochemical examinations, which are not achieved by clinical examination alone [73], and a minimum of three microscopic signatures should be observed, including spindle or oval cells in a plexiform growth pattern, rich and small-sized vasculature, and abundant myxoid matrix. The benignity of PF could be speculated by its limited atypia and low mitotic rate [89]. The plexiform pattern is highly characteristic of PF, so the designation of a tumor without plexiform growth pattern as PF is highly unlikely. Immunohistochemically, PF is almost always positive for vimentin and SMA and variably positive for desmin, caldesmon, and CD10. Negativities for DOG-1, CD117, CD34, S-100 protein, EMA, and ALK should be examined to exclude similar mimicking conditions.

The most important differential diagnosis of PF is GIST, especially myxoid variants of GIST with spindle-cell histology [77, 89]. Most PF cases were initially treated based on a suspicion of GIST, which is the most common gastrointestinal mesenchymal tumor and potentially fatal [77, 82]. Microscopically, although not totally impossible [89], a plexiform pattern is highly unusual for GIST [9]. In addition, the characteristic immunoprofiles of CD117, CD34, and DOG-1 immunoreactivities and C-KIT or PDGFRA mutations of GIST are adopted widely in routine pathological practice [82].

Other pathological differential diagnoses, based on spindle cell morphology and myxoid stromal background, include sarcomatoid carcinoma, peripheral nerve sheath tumor, inflammatory fibroid polyp, and inflammatory myofibroblastic tumor. Primary or secondary sarcomatoid carcinoma with spindle tumor cells and myxoid stroma could be sometimes mistaken as gastrointestinal mesenchymal neoplasm. A clinical cancer history, a more malignant cytological feature, such as brisk mitotic or apoptotic activities, positive epithelial immunoreactivities, and markers for possible metastatic origins, such as TTF-1 for pulmonary origin, are significantly conducive to the correct diagnosis [90].

Peripheral nerve sheath tumor includes benign schwannoma, neurofibroma or ganglioneuroma, and malignant peripheral nerve sheath tumor (MPNST); some variants also demonstrate a plexiform growth pattern [89]. Neurogenic markers, such as S-100 protein, SOX10, and neurofilament, highlight nerve sheath differentiation that is absent in PF [91, 92].

Inflammatory fibroid polyps consist of bland-looking spindle cells arranged in perivascular whorled pattern in a myxoedematous inflammatory stroma with mostly eosinophils. Positive CD34 immunoreactivity is the key characteristic of this rare tumor, which should be negative in PF except for vascular endothelial cells [93].

Inflammatory myofibroblastic tumor is characterized by monotonous spindle cells arranged in fascicles or vague whorls in an inflammatory and edematous stroma full of neutrophils, eosinophils, or lymphoplasma cells. Although the myofibroblastic nature of an inflammatory myofibroblastic tumor is similar to that of PF by morphology and immunohistochemical studies, the lack of a plexiform growth pattern, a predominantly inflammatory cellular microenvironment, and positive ALK immunoreactivity help to distinguish inflammatory myofibroblastic tumor from PF [94].

9. Treatment

The mainstream treatment of PF is surgical removal, while medical treatment serves an assistant role for symptomatic management. Among the 121 reported cases, treatments were available in 99 cases and not provided in 22 cases. Partial gastrectomy (N=30) and distal gastrectomy (N=26) are the most frequently performed surgical treatments for PF, followed by local resection (N=12), subtotal gastrectomy (N=10), wedge resection (N=7), submucosal dissection (N=6), antrectomy (N=3), partial duodenectomy (N=2), nonsurgical follow-up with only endoscopic biopsy (N=2), total gastrectomy (N=1), and laparoscopic cholecystectomy (N=1). A laparoscopic operative technique was performed in 10 cases, endoscopic resection in 9 cases (including 1 thoracoscopic resection), and laparoscopic endoscopic cooperative surgery (LECS) in 4 cases. None of the surgically treated cases presented with severe postoperative complications, except for a 63-year-old male patient who had experienced recurrent GI bleeding for 17 years with a duodenal PF and had undergone pancreas-preserving duodenectomy of the first 2 portions, complicated by a low output pancreatic-skin fistula which had totally drained after 4 months. Secondary procedures included Billroth’s operation I (N=3), Billroth’s operation II (N=2), Roux-en-Y anastomosis (N=2), and omentectomy (N=1).

Conservative management included endoscopic resection and nonsurgical intervention. Since PF is currently considered a benign disease (though not yet verified by convincing evidence), conservative management may be suitable for PF patients, and particularly for the elderly or selected patients with surgically contraindicated comorbidities [72]; at least, more conservative surgical management than partial gastrectomy could be feasible [23]. However, vascular and lymphatic invasion were reported by Miettinen et al. and Kawara et al. [11, 60], and PF usually develops in a nodular and plexiform pattern with unclear tumor margins [1, 30, 64], suggesting that the possibility of malignancy or local recurrence cannot be fully excluded [9, 73]. Therefore, regardless of the operative technique, we suggest that complete resection still be the first consideration when treating PF rather than consideration of the conservativeness of the operative technique [30, 64, 71]. PF cases with severe clinical presentations, such as perforation [1, 21], infection [36], or considerable hemorrhage [53, 58, 63, 74], and with malignant suspicion, such as significant body weight loss [11, 72] or rapid tumor growth [16], should be addressed with aggressive radical surgical treatment rather than conservative management, despite the benign pathological results.

10. Prognosis

PF shows a benign biological behavior [18, 73, 74], with a low proliferation rate and low mitotic rate, and no local recurrence or distant metastasis has been reported so far [74]. However, no consensus has been reached whether PF is actually a benign tumor, and no cases have confirmed that malignant change does not occur, so confirmation of the benign nature of PF still requires longitudinal observational studies with sufficient case numbers. Nevertheless, for the time being, PF should be considered a benign tumor, in response to the strategy of conservative management.

Of all the 121 reported cases, follow-up was not reported in 37 cases, and the follow-up period was not reported in 4 cases. No malignant change, local recurrence, or PF-related mortality was reported. Most of the cases were uneventful after treatments, and among the cases that had follow-up periods, the uneventful or alive duration ranged from 0.75 to 396 months, with an average of 44.29±72.5 months and a median of 15 months. An 81-year-old female who underwent nonsurgical management also had her symptoms resolved 3 months after [72], and a 45-year-old male in Lai’s study who underwent only endoscopic biopsy without further resection also led an uneventful life at 0.2-year follow-up [77]. Three cases were reported to have died for unknown causes at 2 months, 14.5 years, and 25.5 years after diagnosis [11]. Vascular or lymphatic invasion was noted in 5 cases, none of which had adverse significance on prognosis [11, 60].

11. Conclusion

PF is a rare mesenchymal tumor with increasing clinical attention and occurs mostly but not exclusively in the GI tract. Typical clinical presentations are nonspecific GI signs or symptoms, or upper GI bleeding. Endoscopic biopsy is recommended for visualizing the microscopic features of PF with benign cytological traits, and immunohistochemical staining is required for diagnosis as well as for exclusion of GIST. Surgical local excision is the main treatment; however, more conservative management is suggested within an individually reasonable range because of its very good prognosis.

Conflicts of Interest

The authors declare that there are no conflicts of interest regarding the publication of this article.

Authors’ Contributions

Research idea and study design were accomplished by Chih-Jung Chen; acquisition of data was the responsibility of Hsuan-An Su; data analysis and/or interpretation were done by Hsuan-An Su, Hsu-Heng Yen, and Chih-Jung Chen; drafting of manuscript was performed by Hsuan-An Su; critical revision was carried out by Hsu-Heng Yen and Chih-Jung Chen; supervision or mentorship was conducted by Hsu-Heng Yen and Chih-Jung Chen. Each author contributed important intellectual content during manuscript drafting or revision and accepts accountability for the overall work by ensuring that questions pertaining to the accuracy or integrity of any portion of the work are appropriately investigated and resolved.

Acknowledgments

This work was supported by the research grants from Changhua Christian Hospital (grant numbers: 108-CCH-IRP-018 and 106-CCH-IRP-030). The financial support is gratefully acknowledged.

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