Sarcoma

Review Article

Benign Smooth Muscle Tumors (Leiomyomas) of Deep Somatic Soft Tissue

Table 1

Summary of case series reporting the clinicopathological features of leiomyomas of deep somatic soft tissue.


	Authors; year of publication
	Billings et al.; 2001 [10]	Kilpatrick et al.; 1994 [9]

Clinical feature
Age	Middle-aged adults (median, 44 years; range, 12–55 years)	Median, 35 years; range 14–62 years
Gender	M = F	M = F
Anatomical site	Deep somatic soft tissue of the lower extremity, upper extremity, trunk, axilla, and back	Extremities was the most common site

Histological feature
Architecture	Well-marginated; fascicular architecture	Well-defined circumscription; fascicular architecture
Lesional cells	Mature-appearing smooth muscle cells with abundant eosinophilic cytoplasm	Spindle cells with mostly uniform, round-ended, elongated nuclei, and tapering eosinophilic cytoplasm
Nuclear atypia	Absent; minimal atypia of a focal nature acceptable	Absent
Mitotic count	Absent or very low (≤4 mitoses/50 HPF and ≤1 mitosis/50 HPF in the majority)	≤1 mitosis/50 HPF
Atypical mitotic figures	Absent	Not described
Coagulative tumor necrosis	Absent	Absent
Other findings	Stromal hyalinization (majority of cases); prominent stromal calcification (some cases); degenerative nuclear changes	Dystrophic calcification (some cases); degenerative nuclear changes (some cases)

IHC
ER and PR	Negative	Not described

Authors’ conclusion	SMTs of somatic soft tissue that lack atypia, necrosis, and mitotic activity can with reasonable confidence be labeled leiomyomas	The presence of any mitoses in SMTs of subcutaneous or deep soft tissue should be regarded as indicative of potential malignancy; WLE and careful F/U advised

M, male; F, female; HPF, high power fields; IHC, immunohistochemistry; ER, estrogen receptor protein; PR, progesterone receptor protein; SMTs, smooth muscle tumors; WLE, wide local excision; F/U, follow-up. The authors concluded that a smooth muscle tumor of somatic soft tissue with 1–5 mitoses/50 HPF should be regarded as “leiomyoma of uncertain malignant potential.”