Malignant granular cell tumor metastatic to the orbit

Abstract

ObjectiveMalignant granular cell tumor is a rare type of soft tissue sarcoma. To our knowledge, ocular (eyelid) involvement has been described in only two cases. Herein, we report the clinicopathologic features of an unusual case of malignant granular cell tumor metastatic to the orbit. DesignObservational case report. MethodsRetrospective review of the medical record and the histopathologic and electron microscopic findings and review of the literature. ResultsA 72-year-old man with biopsy-proven granular cell tumor in the cervical region was initially seen with proptosis and motility disturbance. A magnetic resonance imaging scan showed a large intraconal mass, and biopsy of the orbital mass revealed granular cell tumor. Histopathologic examination of the primary neck tumor and the orbital mass revealed increased nuclear atypia and pleomorphism in the consecutive lesions. The morphologic impression of granular cell tumor was also supported by the immunohistochemical demonstration of S-100 protein expression and ultrastructural findings typical of granular cell tumor. Six months after the orbital involvement, systemic workup revealed multiple apparent bony and lung metastases. ConclusionsWe report the first malignant granular cell tumor metastatic to the orbit and suggest the inclusion of this tumor in the differential diagnosis of metastatic orbital lesions.