OBJECTIVE: To tell to the rare occurrence of plexiform malignant degeneration of one neurofibrome in the cervical region in a carrying patient of Neurofibromatosis type 1 (NF 1), emphasizing the use of 18F-FDG PETSCAN as diagnostic method and the surgical resection as treatment of choice. Story of the case: C.H.V.D, 18 years, masculine, recent diagnosis of NF1, directed to the service of Surgery of Head and Neck of the Santa Casa of Belo Horizonte with story of right cervical mass has 2 years, presenting growth fast e local pain in last the 3 months. It evolved with dyspnea for extrinsic tracheal compression, being interned for propaedeutic. Carried through 18F-FDG PETSCAN, that evidenced injury with accented hypermetabolism in suggestive cervical region of malignant degeneration. It was submitted to the surgical resection of the tumor that included segment of the vacant nerve. Pathological anatomo evidenced fusocellular neoplasias with peripheral, atypia areas of plexiform standard and has taken free increase of the cellularity, edges. The patient meets in ambulatorialy accompaniment has 6 months without return signals. CONCLUSION: the risk of malignant transformation of one neurofibrome in patient with NF1 is of 8 13%. The cervical region is the place less common for the development of Malignant Neoplasia of Case of Peripheral Nerve. Malignant degeneration of neurofibrome vagal is extremely uncommon. The Revision of literature in English language presents the register of only 5 described cases until the moment. The precocious diagnosis and the surgical resection are praised for optimize of the effectiveness of the treatment.