Track: Case Reports

Abstract:

Spindle cell lipomas (SCL) are a heterogeneous group of lipomatous and fibroblastic tumors that typically arise in the regions of the posterior neck, back, and shoulder in middle-aged to older men. Several described variants exist such as plexiform, vascular fibrous, pseudoangiomatous, composite forms, and rare 'low-fat' and 'fat-free' subtypes. Specifically, the pseudoangiomatous SCL variant is characterized by spindle-shaped cells, adipocytes, ropey collagen, and slit-like pseudovascular spaces. The presence of pseudoangiomatous and concurrent low-fat subtypes is extremely rare. This study presents a 42-year-old man with a 2.5 cm mass on his neck. Lymphoma was initially suspected; therefore, a lymphoma workup was initiated. Grossly, the specimen appeared tan with scant adipose tissue and myxoid cut surfaces. Histopathologic examination demonstrated a neoplasm with some areas showing adipocytes with admixed spindled cells in an eosinophilic to myoxid stroma. Other areas revealed thick eosinophilic collagen bundles lined by concentrations of the spindle cell nuclei, imparting a sinusoidal vascular appearance, so called “pseudoangiomatous areas.” Immunohistochemistry stains revealed that monomorphic spindle cells were diffusively positive for CD34 in the lesion and negative for D2-40. Factor 8 and CD31 showed scattered capillaries in the pseudoangiomatous areas but were negative in the lesion. S100 stained scattered adipocytes. Flow cytometry revealed no evidence of B-cell light chain restriction or an abnormal T-cell immunophenotype and thus did not identify any abnormal lymphoid cell population. The simultaneous presence of both pseudoangiomatous and low-fat variants within one lesion makes diagnosis even more challenging and highlights the importance of awareness of this rare presentation

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Kshitij Arora