Malignant Triton tumor in the retroperitoneal space associated with neurofibromatosis type 1: a case study.

We report an extremely rare case of malignant Triton tumor developing in the retroperitoneal space in a patient with neurofibromatosis type 1. A 21-year old man who had been diagnosed with neurofibromatosis type 1 was admitted to our hospital with the chief complaint of a palpable abdominal mass. Abdominal computed tomography revealed a huge heterogeneous tumor measuring approximately 17 cm in diameter occupying the left retroperitoneal space, and numerous metastatic lesions between the left psoas muscle and the left thigh with dissolution of the left hip joint. After the diagnosis of a retroperitoneal malignant neurogenic tumor, resection of the tumor with reconstruction of the abdominal aorta was conducted, followed by postoperative transarterial infusion chemotherapy. The histopathological diagnosis was malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation, namely malignant Triton tumor. Postoperative chemotherapy was in vain and the patient died 14 months after the surgery as a result of lung metastasis.