Oculomotor disturbances due to granular cell tumor.

Primary granular cell tumor of the orbit is a rare type of neoplasm. The tumor is frequently associated with extraocular muscles, and eye motility limitation is an unavoidable complication after its surgical removal. The objective of the present article is to review the literature on primary granular cell tumors of the orbit and to report a case of this uncommon neoplasia. Granular cell tumor is a benign lesion encountered in most cases (58.3%) in the inferior aspect of the orbit. Extraocular muscle involvement occurs in 72.2% of the patients, and diplopia is present in 77.1% of the cases. The inferior and medial recti are the most affected muscles (38.5% and 26.9%, respectively). Surgical excision is the only modality of treatment, but diplopia persists in 73.3% of the cases. In conclusion, granular cell tumor is a benign lesion but involves a high rate of extraocular muscle morbidity.