Introduction: Primary malignant neoplasms of nerve sheath origin are rare, highly aggressive tumours that account for no more than 5% of all soft tissue sarcomas. In the head and neck where the great majority of peripheral nerve neoplasms are benign, as in the rest of the body, malignant peripheral nerve sheath tumours (MPNSTs) are unusual lesions.
Patient: A case of a large MPNST is reported, which originated in the left temporalis muscle of a 74-year-old man who did not suffer from von Recklinghausen's disease. It had been treated as an abscess for a long time.
Discussion: The clinicopathologic properties of this neoplasm have been widely discussed and the emphasis is on the need for its early identification since the tumour's non-specific symptoms may result in delayed diagnosis and treatment.
Conclusion: To date, to our knowledge, no case of MPNST located in the temporalis muscle has been described. The rarity of the tumour along with its clinical appearance and the vague symptoms may result in delayed referral and thus the tumour being quite large when diagnosed.