Granular Cell Tumors (GCTs) of the orbit are rare-entity soft-tissue tumors, and few reports have been published in the literature. The treatment of the choice is total excision. Early diagnosis prior to surgery is valuable for the distinction of malignant from benign tumor.

We report a case of a 55-year-old woman with a solitary slow-growing mass in the right orbit with the involvement of the rectus inferior muscle, and present a review of the recent literature. The lesion had a diameter of 1 cm and was noticed 2 years before the examination. Excisional biopsy confirmed the diagnosis of GCT. The tumor was resected through a retroseptal transconjunctival approach. The final histological examination revealed findings characteristic of GCT, including positive reaction for protein S-100, SOX10, and calcitonin and negative reaction for desmin, myogenin, Smooth Muscle Antigen (SMA), Melan-A, and HMB-45. There were no signs of malignancy in this sample. Disturbance of motility was not noted by the patient after surgery.

GCT should be included in the differential diagnosis of intraorbital lesions, particularly those that involve the orbit muscles. A biopsy is recommended before surgical resection, to exclude malignancy and prevent radical resection.