Myofibromas and myofibromatosis of the oral region: A clinicopathologic analysis of 79 cases

The clinicopathologic features of 79 myofibromas or myofibromatoses of the oral and maxillofacial region were studied. The case studies were taken fro m the files of the Armed Fortes institute of Pathology. The tumors affected 44 males and 33 females (gender was unknown in 2 cases). The patients' age s at diagnosis ranged from birth to 84 years, with mean and median ages of 26.6 and 22 years, respectively. Four patients had infantile myofibromatosi s; 2 had extraoral bone lesions and 2 had multiple subcutaneous rumors. In descending order, tumors involved the mandible, tongue, lips, check or bucc al area, maxilla or palate, pterygomandibular raphae, floor of mouth, and s ubmandibular gland. One third of the tumors affected the bones of the jaws; 12 were central and 15 were cortical or periosteal. All medullary tumors o ccurred in patients under age 18. On gross examination, the lesions were fi rm, homogenous or whorled, white-grey fibrous masses that ranged in size fr om 0.5 to 5.0 cm. Microscopically, all tumors demonstrated a pattern of nod ules or bundles of spindle cells separated by areas of greater cellularity and crescent-shaped vascular spaces. Distinct hemangiopericytoma-like areas were present in 22 cases. Despite apparent circumscription, the tumors com monly infiltrated and entrapped adjacent muscle, nerve, or salivary tissue. Immunohistochemically, 37 of 37 and 39 of 39 tumors stained positively for alpha-smooth muscle actin and muscle-specific actin, respectively, with th e former eliciting a more intense reaction. Eight of 8 tumors were weakly p ositive for CD68, and one case stained focally with S-100 protein. No desmi n staining was present in 36 tumors examined. Diagnostic interpretations by the pathologists seeking consultation were malignant or aggressive tumors in 31 cases and other benign conditions in 26. Nine were interpreted as myo fibromatosis and 13 offered no interpretation. Thirty-two patients were ali ve and free of tumor an average of 42 months after initial diagnosis. Four patients had one recurrence Each, and 2 had lesions recur twice. Myofibroma s are relatively common soft tissue tumors of the maxillofacial region, whi ch have been misinterpreted as malignant or aggressive lesions.