Abstract

Anaplastic spindle cell carcinoma (ASCC) of the head and neck mucosa is a rare variant of squamous cell carcinoma (SCC) composed of dedifferentiated SCC with sarcomatous features. Diagnosis of ASCC can be challenging due to its pleomorphic cytology and variable immunohistochemical profile. Prompt and accurate diagnosis of ASCC is important given its often aggressive clinical behavior and different therapeutic management compared with conventional SCC and other mucosa-based spindle cell malignancies. We present a case of a 78-year-old female with a 1-year history of a growing asymptomatic nodule on the right lateroventral surface of the tongue. Clinical exam demonstrated a firm mucosa-colored polypoid nodule with a clinical impression of traumatic fibroma. Histopathology showed pseudoepitheliomatous hyperplasia and ulceration of the overlying epithelium with underlying sheets of large plump pleomorphic epithelioid and spindled cells in a vaguely fascicular pattern. Initial immunohistochemical (IHC) staining was negative for P63, CAM5.2, S100, SOX-10, DESMIN, CD31, CK19, and showed patchy weak granular cytoplastic staining with SMA. Given previous nondiagnostic studies, additional IHC staining was performed and was positive for AE1/3 and CK903, confirming the diagnosis of ASCC. This case is presented due to the rarity of ASCC of the head and neck mucosa, and to highlight its variable cytokeratin IHC staining. We wish to emphasize the utility of performing additional cytokeratin studies if previous screening is negative as this was imperative for the diagnosis in our case.

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