Scalp malignant peripheral nerve sheath tumor (MPNST) with bony involvement and new bone formation: case report.

Malignant peripheral nerve sheath tumors (MPNSTs) are rare neoplasms, usually arising from somatic soft tissues or peripheral nerves. Primary MPNST of the scalp is extremely rare, with only a single case reported so far. Here, we describe an unusual case of scalp MPNST in a 50-year-old male. The tumor was associated with bony projection, intracranial extension and underlying bone destruction. The tumor was treated with complete surgical excision followed by adjuvant radiotherapy. Histologically, the tumor showed malignant spindle cells with focal S-100 positivity on immunohistochemistry and a diagnosis of MPNST was made. This case is being reported for its rarity and presence of associated bony projection, which to the best of our knowledge, has not been described before in soft tissue sarcomas.