Successful treatment with doxorubicin and ifosfamide for mediastinal malignant peripheral nerve sheath tumor with loss of H3K27me3 expression.

Malignant peripheral nerve sheath tumor (MPNST) in the thorax is an extremely rare disease, and half of all cases of MPNST are associated with neurofibromatosis type I. Sporadic intrathoracic MPNST is difficult to diagnose and treat. Because of the rarity of intrathoracic MPNST, the optimal method of diagnosis and the efficacy of chemotherapy are unknown. Herein, we present a case of inoperable mediastinal MPNST, in which the diagnosis was immunohistochemically made by the loss of H3K27me3 expression in a transbronchial needle biopsy specimen. The patient showed a good response to doxorubicin plus ifosfamide chemotherapy. The present case highlights that MPNST should be included in the differential diagnosis of non-posterior mediastinum thoracic lesions, and that appropriate diagnosis and treatment for intrathoracic MPNST should be considered in patients with a thoracic mass.