Intractable sciatica due to intraneural nodular fasciitis detected by positron emission tomography

Case report.

To describe a patient with nodular fasciitis in the sciatic nerve, detected by positron emission tomography (PET).

Severe sciatic pain is commonly caused by lumbar disc herniation, lumbar spinal stenosis, or neoplastic lesion. These lesions are usually diagnosed by plain radiograph, myelography, computed tomography, and magnetic resonance imaging.Nodular fasciitis is a benign connective tissue tumor usually presenting as a firm, rapidly-growing lesion, occasionally arising in the forearm. Only 5 cases of intraneural nodular fasciitis have been reported in the published data, and although some have demonstrated mild neuropathy, none have shown nodular fasciitis with intractable sciatica.

A 37-year old woman experienced severe sciatica after hitting her left buttock hard on the edge of a bathtub. Physical examination demonstrated intense radiating pain from the left buttock to the lateral calf. There was weakness in the sciatic nerve innervated musculature. She was diagnosed with piriformis syndrome in a local hospital. However, the symptoms remained unchanged after surgery, releasing the piriformis. Conventional imaging of the sciatica including plain radiograph, computed tomography, and magnetic resonance imaging of the spine showed a return of abnormal findings.

PET detected an abnormal lesion in the sciatic nerve in the posterior compartment of the patient's left thigh, indicating an intraneural tumor in the sciatic nerve. Subtotal resection was achieved and histologic evaluation of the specimen showed the typical features of nodular fasciitis. After surgery, the patient was relieved of all symptoms, with no evidence of recurrence at the recent 2-year follow-up.

This is the first reported case of intraneural nodular fasciitis presenting with severe radiculopathy. Nodular fasciitis should be considered in the differential diagnosis of severe sciatica. PET may be a useful tool for diagnosing sciatica of unknown origin that cannot be identified using conventional imaging tools.