[Mass on the neck].

Malignant peripheral nerve sheath tumors (MPNST) are rare. But especially in patients with known neurofibromatosis type 1 (von Recklinghausen), this entity of tumors should not be forgotten. The indication for open biopsy or excision should be made generously. In the following, we report a rare case of MPNST, which highlights the importance of rapid diagnosis and treatment.