Surgical Treatment for Orbital Leiomyoma and Its Possible Origin

Objective: Orbital leiomyoma is a rare benign tumor derived from smooth muscle cells and its origin is still unknown. Surgical resection is recommendable; however, recurrences have been reported in ophthalmological surgeries. Here we present the possible hypothetical origin of orbital leiomyoma and the usefulness of neurosurgical approach.

Patient: A 31-year-old man presented with left eye pain and exophthalmos, which were observed three times over 12 years and diagnosed as intraorbital varix. On examination, eye of movement (EOM) disturbance, ocular hypertension, and visual disturbance were also observed. Computed tomography revealed a high density tumor (diameter, 3 cm) in the left orbit near the apex. In magnetic resonance imaging, it was visualized as a heterogeneous low- to isointense on T1-weighted image (WI) and high-intense on T2-WI, and as a depressed lateral rectus muscle without optic nerve encasement. Digital subtraction angiography showed no tumor stain, feeding artery, or abnormal vessel.

Results: Conservative treatments did not ameliorate his symptoms. Hence, we did the surgery by left orbit-zygomatic approach, which exposed the lesion widely. The lesion obtained hematoma and thickened periorbita with granulation. Both were totally removed. EOM and light perception recovered after surgery, and recurrence has not been observed. Pathological diagnosis was leiomyoma, and specimens showed disarray of smooth muscle fibers continuous to periorbita, suggesting that periorbita might be the tumor origin.

Conclusion: This tumor with uncommon features is the first report that periorbita is the possible origin of orbital leiomyoma. An orbitozygomatic approach would be useful for complete resection to avoid recurrence.