
Introduction: Neurofibromatosis Type 1 (NF1) is a multi-organ disorder of genetic origin, transmitted through the autosomal dominant modality. Peripheral nervous sheath malignant tumors (PNSMT) are rare highly aggressive soft tissue sarcomas, they represent 5-10% of soft tissue sarcomas (2) and are the main complication of NF1. We report in this article a giant PNSMT observation complicating a NF1. Observation reported: This is a 50 years-old woman with cutaneous neurofibroma since adolescence and no other specific antecedent. Plexiform neurofibroma of the left flank increased rapidly in size, becoming ulcero-necrotic and inflammatory, and malodorous. The examination showed coffee-milk and cutaneous neurofibromas on almost the whole body, pleoform neurofibromas in the occiput, vertex and vulva, and budding, whitish, ulcero-necrotic, pedicled, hemorrhagic, 210mmx170mm at the left flank. In the back of the eye, nodules of Lish were present. The biopsy of the giant tumor was in favor of aMPNST. Chest x-ray and abdominal and pelvic ultrasound were normal. The patient died before the surgery.