Orbital perineurioma in the setting of dacryocystitis

A benign orbital perineurioma was discovered just posterior to the lacrimal sac during surgery for recurrent bacterial dacryocystitis in an 83-year-old woman. The tumor was circumscribed but nonencapsulated and located exterior to the lacrimal sac mucosa. It was composed of cytologically bland spindle cells organized in graceful, elongated, and twisted bundles reminiscent of a storiform pattern. Immunohistochemical staining displayed a diagnostic pattern of Claudin-1, GLUT-1, and epithelial membrane antigen positivity. Malignant transformation is virtually unknown, even with incomplete excision. The differential diagnosis includes neurofibroma, schwannoma, leiomyoma, solitary fibrous tumor (CD34 positive), and low-grade fibromyxoid sarcoma.