Neuromuscular Choristoma of the External Peroneal Nerve: A Case Report and Review of the Literature

Case: We report the case of a 4-day-old male infant with a Choristoma of the External peroneal nerve. In the second week of life, he developed an acute peroneal nerve neuropathy. An open biopsy was needed to confirm the diagnosis and decompression of the External peroneal nerve were performed. After 3.5 years of follow-up, the child has complete passive ankle motion but not active dorsal flexion. The US reveals that the child's normal growth is related to small tumor growth. Conclusion: Choristomas are infrequent benign tumors that arise from the peripheral nerves formed by mature skeletal muscle elements mixed with mature neural elements. They present as solitary lesions and are located in cranial nerves, spinal cord and large peripheral nerves such as median nerve, brachial plexus and sciatic nerve. In this case report, we describe the first case reported, as far as we know, of a Choristoma arising from the External peroneal nerve in a newborn, focusing on the difficulties on diagnosis and treatment and we have carried out a systematic review of the literature.