Glomus Tumor of the Sciatic Nerve: An Extraspinal Cause of Sciatica.

Glomus tumors are small, benign tumors that arise from glomus bodies, structures found normally within the dermis that assist in temperature regulation via their vasoconstrictive response to sympathetic stimuli. Glomus tumors are found typically in the hand and are classically a cause of focal pain and temperature sensitivity. They often present as a small blue lesion seen under the nail bed of a finger or a toe and cause point tenderness. Glomus tumors of peripheral nerves are exceedingly rare and can lead to disability akin to compressive neuropathy when present. This case report explores the unusual presentation of a rare and large glomus tumor of the sciatic nerve. The patient presented with symptoms such as those mentioned above and was assumed to have sciatica emanating from spinal and neuroforaminal stenosis. Although she repeatedly and appropriately sought medical attention for her condition, she was improperly diagnosed and ultimately experienced a significant deterioration of her function, eventually undergoing an unnecessary surgical procedure. On referral to the authors' institution, the patient was evaluated and found to have a glomus tumor involving the sciatic nerve. This is the largest glomus tumor of a peripheral nerve that has been reported to date. Although the patient's presentation was insidious and her diagnosis was uncommon, this underscores the importance of developing a differential diagnosis based primarily on a thorough physical examination and, only then, correlating imaging to clinical findings. Additionally, given the atypical presentation and intractable course of this patient's condition, the examiner must consider neoplastic entities and space-occupying lesions as part of the differential diagnosis. [Orthopedics. 2018; 41(1):e151-e153.].