A 36-year-old man had never been diagnosed with infantile myofibromatosis despite his lifelong history of multiple tumors of various diagnoses. He presented with simple partial seizure and progressive right finger paresis. A series of brain magnetic resonance imaging scans revealed a rapidly growing lesion at his left frontal convexity, which corresponded to a high uptake area on a 18F-fluorodeoxyglucose-positron emission tomography scan, highly suspicious of malignancy. He underwent complete tumor resection and his symptoms quickly resolved postoperatively. The pathological diagnosis was myofibroma with a MIB-1 labeling index of 1%−2%. A retrospective review of his previous tumors demonstrated the same pathology, which led to the diagnosis of myofibromatosis. Follow-up magnetic resonance imaging illustrated stabilization or regression of other preexisting lesions as well as formation of a new intracranial lesion.
The discrepancy between rapid tumor growth associated with increased uptake on metabolic imaging and benign pathologic findings with a low proliferative index is noteworthy and should be recognized in the management of an intracranial lesion in a patient with infantile myofibromatosis. Given de novo formation of a lesion in this adult patient, long-term follow-up is essential in this disease.