Orbital neuromuscular hamartoma with cavernous sinus involvement: A case report of a rare trigeminal nerve tumor.

Background: Neuromuscular hamartoma (NMH), or benign triton tumor, is a uncommon peripheral nerve lesion of mature skeletal muscle fibers mixed with nerve elements. Trigeminal nerve involvement is rare, especially with combined intraorbital and intracranial extension. Case Description: A 35-year-old woman with a 6-year history of right-sided proptosis, retro-orbital pain, diplopia, and visual impairment. A prior biopsy suggested schwannoma, and radiotherapy was performed without improvement. Examination showed right cranial nerve III, IV, and VI palsies. Magnetic resonance imaging revealed a heterogeneous mass extending from the orbit through the superior orbital fissure into middle cranial fossa and cavernous sinus. The lesion was treated with a staged surgical approach with intracranial resection followed by orbital exploration with evisceration of the nonfunctional eye. Histopathology confirmed NMH. Postoperative imaging showed gross-total resection without recurrence. Conclusion: NMH of the trigeminal nerve is a uncommon entity that can mimic more aggressive neoplasms on imaging, leading to misdiagnosis. Accurate histopathological evaluation and multidisciplinary decision-making are crucial. For orbital and cavernous sinus involvement, staged surgery can provide effective disease control.