Neuritis ossificans mimicking a malignancy in a child: case report and literature review

We present the case of a child with neuritis ossificans after acute trauma, treated conservatively. The aim of the review is to compare several parameters in this disease. Emphasis is placed on the clinical-radiological features distinguishing neuritis ossificans from malignancy to avoid unnecessary biopsy and surgery.

A literature review was performed. Only 18 cases were described. Except for one, all describe adults, and none had acute trauma. Nearly all were treated surgically.

Our 13-year-old patient presented with posterior knee pain after trauma. MRI demonstrated a mass within the tibial nerve with oedema, some lymph nodes and increased avidity on ¹⁸fluoro-2-deoxyglucose-positron emission tomography. These findings can be reactive but also associated with malignancy. However, eggshell-like calcifications in the periphery of the mass were seen on CT. Biopsy and resection were proposed. Follow-up visits over the next weeks showed remarkable clinical improvement. Wait-and-scan was advised after international discussion. Follow-up imaging after 2 months showed resolution of the oedema and volume reduction of the mass, suggesting a benign pathology. Diagnosis of neuritis ossificans was proposed based on the clinical and radiological features. There was a favorable course with no complaints after two months. Imaging after seven months showed an almost complete regression.

Neuritis ossificans should be considered within a painfull (mono)neuropathy. The initial inflammatory phase may mimic malignancy, misleading clinicians toward biopsy or surgery with the risk of nerve damage. As seen in our case, neuritis ossificans can be a self-limiting process. Therefore, conservative therapy should be considered with a wait-and-scan approach.