Case Reports in Pathology

Introduction. Assessment of axillary lymph nodes in breast carcinoma is an important part of staging to guide appropriate clinical management. Lymph node inclusions of different types, including nevoid, squamous, and glandular, are rare but have been reported in multiple different anatomic locations including the axilla. These can result in diagnostic challenges and pose risks of misdiagnoses. Rarely, malignancies may arise intrinsic to otherwise incidental benign nodal inclusions. Case Presentation. We report a case of ductal carcinoma diagnosed within a squamous epithelial inclusion cyst within an axillary lymph node in a patient with pure ductal carcinoma in situ (DCIS) of the ipsilateral right breast. To our knowledge, this is the fifth report in the literature of breast carcinoma confirmed within an axillary inclusion in a patient with pure DCIS. Evaluation of the primary DCIS and lymph node inclusions, by routine and immunohistochemical stains, was performed for assessment. Discussion. The presence of lymph node inclusions can pose a challenge in assessment of benignity and malignancy, on frozen and permanent histologic sections. Pathologists should carefully evaluate lymph node inclusions to ensure that intrinsic malignancies are not missed within rare otherwise benign appearing incidental epithelial rests.

Diffuse large B-cell lymphoma, not otherwise specified (DLBCL NOS) is the most common lymphoid malignancy in the Western world and classically presents as a rapidly enlarging nodal or extranodal mass. Cutaneous involvement by systemic DLBCL NOS is an infrequent clinical presentation, encountered in only 1.5-3.5% of cases, while disseminated cutaneous disease with multiple subcutaneous nodules at the time of diagnosis is unusual and can present a diagnostic challenge. The differential diagnosis when encountering a high-grade B-cell malignancy at a cutaneous site is broad and includes primary cutaneous follicle center lymphoma (PCFCL), primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT), high-grade B-cell lymphoma with MYC and BCL2 rearrangements (HGBCL-MYC/BCL2), and other potential entities which must all be carefully considered before rendering a final diagnosis. In this report, we describe the case of a 69-year-old man who was seen at our hospital due to generalized weakness and was found to have multiple subcutaneous nodules representing disseminated DLBCL NOS. The case was complicated by concurrent monoclonal B-cell lymphocytosis involving the bone marrow.

We describe two cases of rectal herpes simplex virus (HSV) infection in men that clinically mimicked rectal adenocarcinoma. Herpes infection in this location more commonly presents as an anal mass with viral inclusions in squamous epithelial cells. We report these cases to increase awareness of the unusual presentation as a proximal rectal mass with viral inclusions in endothelial cell nuclei. One patient was HIV-positive, and the other one had a history of having sex with men (MSM). Both patients had a thickened rectal wall with prominent lymphadenopathy on computed tomography (CT) scan, suspecting for malignancy. Biopsy showed abundant granulation tissue, necrosis, and inflammatory infiltrate composed predominantly of lymphocytes with admixed numerous plasma cells, eosinophils, and neutrophils. Rare granulation tissue vessels were lined by endothelial cells with nuclear molding and chromatin margination, and nuclei that were positive for HSV immunohistochemistry (IHC). One patient had confirmatory viral culture from biopsy of the ulcerated rectal mass. Both patients had symptom resolution following treatment for HSV. HSV should be considered in the differential diagnosis of rectal inflammatory masses, particularly in immunocompromised, HIV-positive, and MSM patients.

Pleomorphic liposarcoma (PLS) is typically found in the lower and upper extremities. PLS arising in the gastrointestinal (GI) tract is extremely rare. Here, we reported a case of a 71-year-old female with a history of rectal adenocarcinoma presenting with small bowel obstruction. Small bowel resection was performed and revealed a 7.8 cm transmural mass in the jejunum. Histology reviewed a heterogenous epithelioid malignant tumor with intracytoplasmic fatty droplets scalloping the nucleus consistent with lipoblasts in some cells and others with numerous PAS/diastase+intracytoplasmic eosinophilic globules. Scattered multinucleated giant cells were also present. Mitotic count was up to 80/10 HPFs including some bizarre mitotic figures, and Ki67 proliferation index was approximately 60%. Immunohistochemistry demonstrated that the malignant cells were negative for pancytokeratin, CD117, DOG1, SMA, desmin, MyoD1, ERG1, CD34, CD31, SOX10, Melan A, and S100. INI1 was retained. Beta-catenin showed normal membranous staining. P53 was diffusely positive suggestive of mutant phenotype. Fluorescence in situ hybridization (FISH) assay was negative for MDM2 amplification and DDIT3 rearrangement. The overall morphologic and immunohistochemical features supported a diagnosis of high-grade pleomorphic liposarcoma. Diagnosis of PLS can be challenging due to its rarity in GI tract and lack of specific biomarkers, and histomorphology with identification of lipoblasts remains the gold standard.

Mammary Paget’s disease (MPD) is a rare histological condition, accounting for 1-4% of female breast cancers, which may appear either independently (1.4-13% of the cases), or in association with an in situ or invasive ductal carcinoma (approximately 90% of the cases). The purpose of this article is to highlight the histopathological challenges related to the microscopical polymorphism of this disease and the utmost importance of immunohistochemistry in the thorough process of Paget’s disease differential diagnosis. Moreover, the primary objective of this review of literature was to corroborate the existing data concerning the potential peculiar immunohistochemical profile that mammary Paget’s disease might express. We report the case of a 44-year-old female patient, histopathologically diagnosed with HER2-negative MPD accompanying an invasive mammary carcinoma. The histopathological and immunohistochemical approach is derived from the exigency of excluding the possibility of synchronous tumors—a mammary invasive carcinoma, accompanied by another component with MPD phenotypic mimicry. The unexpected negative HER2 reaction is conducted to a primary focus on excluding a malignant melanoma in situ. The absence of MelanA and S100 immunoexpression and lack of pigmentation and clinical aspects infirmed it. Bowen’s disease was invalidated by its rare presentation in the breast cutaneous tissue and the absence of individual risk factors suggestive of an existing immunosuppressive status. In the case of similar morphoimmunohistochemical aspects, significant expression of Ki-67 signals MPD, an immunoreactivity that helped distinguish the cellular population from Toker cells. The great similarity of MPD with other benign and malignant cutaneous tumors might determine delay or misdiagnosis. Thus, the utmost importance of immunohistochemistry is reflected in its prognostic significance and geared towards extending the therapeutic arsenal.

Tailgut cysts are congenital cysts arising in the retrorectal space. They are thought to be benign with variable malignancy risks. We report a case with previous surgical intervention decades prior that had undergone a tailgut cyst excision with surgical complications leading to carcinomatosis. An elderly female (70s) presented with tailbone/pelvic pain. She underwent cyst excision that was complicated by an intraoperative rupture. The cyst was pathologically proven to be a tailgut cyst with adenocarcinoma. She presented 13 months postoperatively to the emergency department with worsening abdominal pain. Imaging was concerning for diffuse omental nodules and narrowing of the proximal sigmoid colon. She was not deemed to be a surgical candidate and was transitioned to hospice care, where she passed away shortly afterward. This case report highlights the utility of complete excision of tailgut cysts and possible complications.