Spontaneous Hip Dislocation Complicating the Management of Malignant Peripheral Nerve Sheath Tumor Arising Within a Plexiform Neurofibroma.

Neurofibromatosis type 1 (NF1) is one of the most common inherited neurological disorders. It can cause plexiform neurofibromas, leading to diffuse enlargement of a nerve or nerves within the body. There are benign in general, however, can cause significant symptoms due to their size, including bony erosion, pain, and joint instability. Unfortunately, they also have the capacity to become malignant by internal transformation into a malignant peripheral nerve sheath tumor (MPNST). The case presented here is a 27-year-old male with NF1 that was followed for years with a pelvic girdle plexiform neurofibroma whose course was complicated by transformation to MPNST and a spontaneous hip dislocation. He underwent excision, Girdlestone procedure, chemotherapy, and radiation. Unfortunately, he subsequently developed lung metastases and is part of a clinical trial with an MDM2 inhibitor and pembrolizumab.