Neuromuscular choristoma of the oculomotor nerve: case report

Neuromuscular choristomas (NMC) are rare benign tumors of the peripheral nerves. We report an NMC affecting the oculomotor nerve.

An 18-year-old girl presented with long-standing intermittent retro-orbital pain and oculomotor paresis. Magnetic resonance imaging scans demonstrated a small nodular lesion on the left oculomotor nerve, similar to the findings for a schwannoma.

The tumor was resected with the parental oculomotor nerve, which was reconstructed using a peroneal nerve graft. Postoperatively, the patient became pain-free, and her oculomotor function partially recovered. Histologically, the lesion consisted of well-differentiated smooth muscle fibers intermingled with mature nerve elements consistent with the diagnosis of an NMC, although the possibility of leiomyoma in this rare location was not excluded completely.

NMC may need histological confirmation for diagnosis if they occur in the intracranial space. The resection is feasible, and the function of the affected nerve can be at least partially restored with the nerve reconstruction.