Clear cell epithelial-myoepithelial carcinoma arising in pleomorphic adenoma of the lacrimal gland.
BACKGROUND: A 63-year-old man had an 8-year history of painless proptosis, which had noticeably increased over the last 2 months. A mass was palpable in the left lateral canthus. Computed tomographic studies showed a globular mass with small foci of calcification involving the lacrimal gland. After an incisional biopsy, a histologic diagnosis of clear cell epithelial-myoepithelial carcinoma was made and an orbital exenteration was performed. FINDINGS: Results of histologic examination of the mass showed a partially encapsulated, clear cell epithelial-myoepithelial carcinoma with an associated pleomorphic adenoma (benign mixed tumor). Immunohistochemical studies disclosed strong immunoreactivity to cytokeratin (AE1/AE3), epithelial membrane antigen, S-100 protein, and alpha-actin. CONCLUSION: Although a clear cell myoepithelial carcinoma rarely has been reported in association with a pleomorphic adenoma of the submandibular gland, to the authors' knowledge, this combination has never been reported in the lacrimal gland, nor has a clear cell epithelial-myoepithelial carcinoma ever been reported in this anatomic location. The differential diagnosis of lesions with prominent clear cells involving the lacrimal gland is extensive and includes clear cell variants of acinic cell carcinoma and oncocytoma, mucoepidermoid carcinoma, and others.