Fibrous histiocytoma of the lacrimal gland.

Fibrous histiocytoma, a primary mesenchymal tumor of the orbit, is known to arise from various ocular and adnexal tissues. We are unable to find a published report of this tumor originating from the lacrimal gland. We report a case of a benign fibrous histiocytoma of the lacrimal gland in an 11 year old girl who presented with painless, progressive eyelid swelling and mild proptosis. Imaging studies revealed a discrete mass in the lacrimal gland region. The tumor was completely excised by anterolateral orbitotomy. Light microscopy showed a spindle cell tumor arising from the lacrimal gland. The tumor cells were arranged in a characteristic storiform (cartwheel) pattern with no pleomorphism or mitotic figures. Immunohistochemically, the tumor cells were focally positive for CD-68 and negative for S-100, smooth muscle actin, vimentin, and CD-34, which ruled out neurofibroma, leiomyoma, solitary fibrous tumor, and hemangiopericytoma. Based on these features, a diagnosis of benign fibrous histiocytoma was made.