Background: Solitary fibrous tumors are rare spindle cell neoplasms that most commonly arise in the pleura. Recently, solitary fibrous tumors of the orbital soft tissues have been described. The authors report the first case of solitary fibrous tumor arising in the lacrimal gland fossa and discuss features that may distinguish solitary fibrous tumor from other lacrimal fossa lesions. Methods: A left lacrimal gland fossa tumor was excised via lateral orbitotomy from a 76-year-old man and analyzed by light microscopy. Immunohistochemical studies were performed using antibodies to CD34, vimentin, epithelial membrane antigen, cytokeratins AE1-3 and Cam5.2, S-100 protein, and actin. Results: The histopathologic features of the tumor were typical of solitary fibrous tumor. A well-circumscribed, variably cellular proliferation of bland spindle cells displayed both 'patternless' and storiform growth patterns. Immunohistochemical studies showed that the tumor cells expressed vimentin and CD34 but did not express epithelial membrane antigen, cytokeratins, S-100 protein, or actin. The patient is free of tumor recurrence after 1 year of follow-up. Conclusion: The authors report the first case of solitary fibrous tumor arising in the lacrimal gland fossa. The clinical presentation of this tumor was similar to that of pleomorphic adenoma (benign mixed tumor) of the lacrimal gland; fortunately, the treatment for both of these lacrimal gland fossa neoplasms is en bloc excision. The histopathologic appearance of solitary fibrous tumor is varied, and immunohistochemical analysis may help in distinguishing solitary fibrous tumor from other lacrimal fossa lesions. Careful follow-up of patients with solitary fibrous tumor is important because recurrence may present years after excision of the primary tumor.
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