A case of well-differentiated liposarcoma of the larynx histologically indistinguishable from spindle cell lipoma

Le résumé fourni par la source

Correctly identifying atypical lipomatous tumors/well-differentiated liposarcomas (WDLs) can be exceedingly difficult, as they account for <0.5% of all laryngeal neoplasms. Diagnosis is further complicated by their morphologic similarity with other more benign lipogenic tumors, such as spindle cell lipoma. We describe a 63-year-old Caucasian man who presented with a left aryepiglottic mass clinically suspicious for a simple cyst. On excision, a frozen section diagnosis of benign fibrolipomatous lesion was reported. Permanent sections revealed an adipocytic neoplasm comprising cellular fibrosis and monomorphic spindle cells, histologically suggestive of a spindle cell/pleomorphic lipoma. Immunostains were positive for CD34 and negative for smooth muscle actin, desmin, and S-100 protein, also consistent with spindle cell/pleomorphic lipoma. However, amplification of MDM2 by fluorescence in situ hybridization confirmed the diagnosis of WDL. The case was reviewed by two soft-tissue pathologists, and they both favored the diagnosis of spindle cell lipoma until reviewing the relevant MDM2 result. The morphology and immunophenotype of WDL have previously been reported as closely related to that of spindle cell lipoma, and this case provides a striking example of how unmistakable these two entities can be on histologic examination alone.

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