NF1 and neoplasm: Malignant Peripheral Nerve Sheath Tumor (MPNST) is an extremely rare tumor (1/100,000) that represents up to 10% of sarcomas, divided into those related to Neurofibromatosis type 1 (NF1), which corresponds to 50% of cases, and sporadic ones.1, 2 The most widely accepted hypothesis today is that NF1-related MPNST arises from a neurofibroma that undergoes multiple genetic and phenotypic alterations until transforming into a malignant lesion.