Myoepithelioma of the lacrimal gland.

A right orbital tumor was excised from a 76-year-old woman. Pathological examination showed that the tumor was composed of spindle to cuboidal cells arranged in a solid to trabecular pattern. Immunohistochemical stains were positive for S-100 protein, muscle-specific actin, cytokeratins MAK6 and AE1,3, and glial fibrillary acid protein and negative for CD34 in tumor cells. Ultrastructural features of tumor cells included microvillous processes, intercellular junctions, and intracytoplasmic filaments with electron densities. To our knowledge, this is the first non-spindle cell myoepithelioma noted to arise in the lacrimal gland. This tumor likely has a similar biological behavior to pleomorphic adenoma (benign mixed tumor).