Proliferative myositis of the masseter muscle

The authors present a case of a 33-year-old white man with a 4-month history of a rapidly enlarging, tender, painful, circumscribed facial mass located in the masseter muscle. CT scan and fine needle aspiration cytology, coupled with clinical assessment, suggested the diagnosis of proliferative myositis. Curative intraoral excisional biopsy was done, thereby avoiding a parotidectomy incision and approach to the lesion. The pathology showed proliferative myositis. A review of the literature revealed 36 cases which indicated that proliferative myositis is a relatively rare etiology of a head and neck mass. Careful clinical, radiologic, and pathologic evaluations were required to make this unusual diagnosis and avoid any unnecessary facial mutilation in its treatment.