Intracranial Infantile Myofibromatosis Mimicking Malignant Brain Tumor: A Case Report and Literature Review

Background Myofibroma is a fibrous tumor of infancy that sometimes affects a single patient in a multiple fashion (infantile myofibromatosis). Its intracranial involvement is extremely rare, and its clinical picture has been poorly characterized. Here we report an interesting case of myofibromatosis with an intracranial lesion that behaved like an aggressive tumor and yet demonstrated very benign pathology. Case Description 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 18 F-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. Conclusions 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.