To present a case of malignant peripheral nerve sheath tumor (MPNST) in the orbit.

A 66-year-old man was evaluated for swelling of the left upper eyelid without pain that developed 2 months earlier. ACT scan and MRI of the orbit showed a large superior orbital mass with adjacent bony erosion, which had a central necrotic area. Incisional biopsy of the orbital mass was performed through a sub-brow incision. Histopathologic examination revealed a hypercellular tumor composed of spindle-shaped pleomorphic cells arranged in a fascicular pattern with necrotic foci. High-power magnification showed mitotic figures and nuclear pleomorphism. Subsequently, a malignant peripheral nerve sheath tumor was diagnosed.

The possibility of malignant peripheral nerve sheath tumor should be considered in the differential diagnosis of an orbital mass which grows rapidly and shows bone invasion. Salvage surgery should be performed promptly to increase the likelihood of long-term survival.