Cytokeratin-positive epithelioid angiosarcoma presenting in the tonsil: a diagnostic challenge.

Primary oral cavity sarcomas are exceedingly rare and may pose a great diagnostic challenge. A 71-year-old woman without history of malignancy or radiation to the head and neck presented with an antibiotic-refractory diffuse painful swelling of the right tonsil necessitating tonsillectomy. Histologic evaluation revealed subtotal replacement of the right tonsil by a high-grade epithelioid neoplasm displaying extensive ulceration, necrosis, and primitive vasoformation. Immunohistochemistry showed strong/diffuse expression of pancytokeratin antibodies KL-1 and Lu5, cytokeratin 8, cytokeratin 18, cytokeratin 19, vimentin, CD31, ERG, and Freund leukemia integration site 1 (FLI-1). High-molecular-weight cytokeratins (cytokeratin 5, 34β12), cytokeratin 7, cytokeratin 13, and cytokeratin 20 were not expressed. Within months, the patient underwent surgical resection of multiple bleeding intraoral and gastrointestinal metastases. She is currently alive with disease 9 months from diagnosis. To our knowledge, this case represents the first well-documented primary epithelioid angiosarcoma of the tonsil. The strong cytokeratin expression in epithelioid angiosarcomas represents a diagnostic pitfall. Thus, awareness of this rare and highly aggressive neoplasm is necessary for distinguishing it from poorly differentiated and acantholytic squamous cell carcinoma and diffuse large cell lymphoma.