To report a case of orbital leiomyoma presenting with proptosis.

A 69-year-old woman presented with a 3-month history of proptosis in her left eye. Intraocular pressure was 17 mmHg in her right eye and 23 mmHg in her left eye. There was a left hypotropia on upgaze. A fundus examination showed retinal folds in the superotemporal area in her left eye. Computed tomography revealed a 2.6 cm-sized well-defined enhancing solid mass in the superotemporal extraconal space of the left orbit, pushing her left eye forward. Lateral orbitotomy, tumor removal, and biopsy were performed. Pathological findings showed a fascicular pattern of benign spindle cells with mild cellular pleomorphism and hyaline degeneration, without mitotic figures. Immunohistochemical stain was positive with smooth muscle actin (SMA), which was compatible with orbital leiomyoma.

Orbital leiomyoma is rare, but it should be considered as a differential diagnosis of orbital tumor when the presenting symptom is proptosis and limitation of ocular movement.