Adult extrarenal rhabdoid tumor of the lacrimal gland.

A 50-year-old man presented with a rapidly growing mass in the area of the right lacrimal gland. An initial erroneous histopathologic diagnosis of a pleomorphic adenoma made on a small-incisional biopsy was later corrected to a malignant rhabdoid tumor when a wide local excision of the tumor was performed. The tumor was composed predominantly of dyscohesive, globoid, and eosinophilic cells, which frequently contained cytoplasmic inclusions. These were demonstrated to be composed of whorls of intermediate vimentin filaments. The tumor cells expressed epithelial membrane antigen as well as cytokeratin. Ultrastructurally, they displayed intercellular junctions and interrupted segments of linear basement membrane material. These findings, together with the development of the lesion within the parenchyma of the lacrimal gland, are suggestive of an epithelial origin. The patient was treated with radical surgery and adjunctive radiotherapy and chemotherapy, which are the recommended treatment modalities for this highly malignant tumor.