Abstract
Pilomatrical carcinoma is a very rare, aggressive cutaneous adnexal tumor. It typically presents as a non-tender firm dermal swelling, most commonly in the head and neck region of middle-aged men. Local recurrence is common and lymph node and distant metastases have been reported. We present a case of pilomatrical carcinoma that presented initially as a metastatic carcinoma of unknown primary. The patient is a 41-year-old male, with no significant past medical history, presenting with a three to four-month history of right neck swelling. Subsequent imaging illustrated a conglomeration of right neck lymph nodes with coarse calcifications, concerning for granulomatous disease versus metastasis. An excisional biopsy of the three putative lymph nodes revealed a tumor comprised of basaloid cells and extensive keratin production with areas of anucleate ghost cells. The basaloid portion demonstrated cytologic atypia and mitoses with areas of calcification and ossification. The tumor exhibited lobular and focally infiltrative architecture and was present in at least two definitive lymph nodes. These features of a keratinizing carcinoma with pilomatrical differentiation were consistent with a metastatic pilomatrical carcinoma. Additional disease was subsequently discovered in the patients oropharynx and he was treated with concurrent chemotherapy and radiation therapy. The unusual presentation of this pilomatrical carcinoma highlights the importance of keeping rare but potentially aggressive tumors in the differential when evaluating skin and soft tissue head and neck tumors.
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