Solitary infantile myofibromatosis of the cranial vault: case report.

Infantile myofibromatosis is a mesenchymal disorder of early childhood characterized by the formation of tumors in the skin, muscle, viscera, bone, and subcutaneous tissue. Although relatively rare overall, it represents the most common fibrous tumor of infancy. The etiology of this disorder is unknown. Infantile myofibromatosis can present as a solitary or multicentric form. With the multicentric form, bone is often involved, but solitary bone lesions account for only 10% of the cases. Imaging findings are not pathognomonic, and the differential diagnosis usually includes eosinophilic granuloma (Langerhans cell histiocytosis), osteomyelitis, metastasis, osteoblastoma, epidermoid cyst, hemangioma, fibrous dysplasia, fibrosarcoma, and meningioma. A histological pattern is typical, but there are no histopathological differences between the solitary and multicentric forms. Solitary lesions generally have a favorable prognosis if totally removed, with a 10% recurrence rate; incompletely resected lesions recur. We report the case of a 9-year-old boy who came to our attention with a solitary infantile myofibroma of the calvarium, appearing as a tight-elastic, lightly tender mass in the left frontal area, eroding both the inner and the outer tables. Histopathologically, the specimens showed a spindle-cell tumor with dense reticulin fiber network and expression of smooth muscle actin. Fifty-eight months MR follow-up after total removal showed no residual or relapse.