[Granular cell tumors of the orbit: diagnostics and therapeutic aspects exemplified by a case report]

Granular cell tumors (Abrikossoff's tumor) are very rare, mostly benign tumors of neurogenic origin which preferentially occur in the upper aerodigestive tract. Granular cell tumors rarely originate in the orbit and are therefore a diagnostic and therapeutic challenge.

A 42-year-old male patient presented to the Orthoptic Department of the University Eye Clinic in Salzburg with motility disturbances and diplopia in the right eye. The clinical examination revealed right-sided exophthalmos and shrinking of the choroid and retina due to a retrobulbar mass. The radiological examination showed an infiltrative tumor 1.7 × 1.3 cm in size in the lower temporal quarter of the orbit. Due to the localization a sonographically controlled fine needle puncture was carried out for preoperative diagnostics by a specialist in clinical cytology. The cytological examination confirmed the presence of a granular cell tumor. The tumor was excised via a conjunctival access route.

Motility testing in the postoperative course control showed an improvement in the findings and the exophthalmos was clearly regressive. Vision improved from 0.5 preoperatively to 1.0 postoperatively. During the postoperative observational period of 12 months no recurrences occurred. Clinical control examinations are planned every 3 months and imaging controls every 6 months.

Granular cell tumors of the orbit should be included in the differential diagnostics of orbital tumors despite the low incidence. A sonographically controlled fine needle puncture is an adequate procedure with respect to the diagnostics and further therapy for poorly differentiated tumors of the orbit with a suspicion of infiltrative growth and for which in toto resection is questionably possible. A complete surgical excision should be the aim of treatment of granular cell tumors. Continuous clinical and imaging control is necessary to enable early recognition of recurrences.