Primary intraosseous malignant peripheral nerve sheath tumor of clavicle: Report of a rare entity.

Abstract: Malignant peripheral nerve sheath tumors (MPNST) are mesenchymal tumors that develop or differentiate from cells of the peripheral nerve sheath. Intraosseous MPNST is extremely uncommon and usually results from secondary invasion. A 17-year-old male presented with pain and swelling over the left collar bone. Imaging revealed an expansile lytic lesion involving the subarticular region of the clavicle with a cortical break and infiltration of the adjacent soft tissues. Biopsy findings were consistent with cellular nerve sheath tumor with significant atypia and mitoses, along with S100 protein immunopositivity indicative of MPNST. The patient was treated with neoadjuvant radiotherapy, followed by wide local excision. To the best of our knowledge, the present case constitutes the first case of a primary intraosseous MPNST involving the clavicle. The case is presented in view of its rarity and with relevant review.