Malignant Cerebellopontine Angle Peripheral Nerve Sheath Tumor with Divergent Mesenchymal (Cartilaginous) Differentiation Presenting with Catastrophic Hemorrhage: Case Report and Review.

Malignant peripheral nerve sheath tumors of the cerebellopontine angle are rare, especially even outside of the context of neurofibromatosis or malignant transformation of previously radiated vestibular schwannomas. This case report describes a case of a presumed vestibular schwannoma without previous radiation or history of neurofibromatosis presenting with progressive hearing loss, facial weakness, growth, and ultimately catastrophic hemorrhage requiring urgent surgery. Histopathology revealed an exceptionally rare malignant peripheral nerve sheath tumor with divergent mesenchymal (chondrosarcomatous) differentiation with few rigorously interrogated cases in the literature. In retrospect, facial weakness, growth, and early intratumoral hemorrhage were harbingers of atypical malignant pathology. We advocate for a heightened index of suspicion, shorter interval follow-up, and consideration of early surgery in such cases in hopes of preventing potentially catastrophic outcomes.