Submandibular gland carcinoma ex pleomorphic adenoma. Report of a case with cytologic features and diagnostic pitfalls.

ABSTRACT

BACKGROUND: Carcinoma ex pleomorphic adenoma is a rare neoplasm of the salivary gland. This lesion, also known as malignant mixed tumor, occurs when a malignant tumor arises in the epithelial component of a pleomorphic adenoma. Reports of fine needle aspiration biopsy (FNAB) diagnosis of malignant mixed tumors are rare and have been limited to cases arising in the parotid. Cytologic features and diagnostic pitfalls of this uncommon neoplasm are presented. CASE A 75-year-old male presented with a nontender submandibular mass. The lesion had been present 12 months, with a recent increase in size. FNAB was performed, and the smears revealed a mixture of benign and malignant areas. The benign portion of the smears showed findings typical of pleomorphic adenoma. The malignant area showed large cells occurring singly and in groups. The malignant cells contained pleomorphic nuclei with irregular nuclear membranes and prominent macronucleoli; cytologically, they resembled cells from a poorly differentiated adenocarcinoma. CONCLUSION: We present the first case of carcinoma ex pleomorphic adenoma of the submandibular gland correctly diagnosed by FNAB. This rare salivary gland malignancy can be accurately diagnosed on FNAB if strict criteria are applied.