Basaloid tumors of the salivary glands.

Basaloid tumors of the salivary glands are a heterogeneous group of benign and malignant lesions characterized by small tumor cells with round or ovoid nuclei surrounded by a thin rim of cytoplasm. Primary salivary gland tumors with this predominant morphology include basal cell adenoma, basal cell adenocarcinoma, cellular pleomorphic adenoma, adenoid cystic carcinoma, and small cell undifferentiated carcinoma. Certain metastatic lesions and nonepithelial neoplasms can also demonstrate a basaloid appearance. Histologic diagnosis based on resected tumors is usually straightforward when the architecture can be adequately assessed. However, in limited biopsies and particularly in cytologic samples, the evaluation can be quite challenging. A systematic approach aided by immunohistochemistry is essential to arrive at an accurate diagnosis.