Melanotic neuroectodermal tumor of infancy successfully treated with metformin: A case report.

RATIONALE: Melanotic neuroectodermal tumor of infancy (MNTI) is a rare tumor originated from neural crest cells with the potential for recurrence and metastasis. The peak age for the disease is during the first year after birth. The current therapy is primarily surgery. The patient reported here is the first case of MNTI treated with metformin. PATIENT CONCERNS: A case of a 4-month-old infant with a history of swelling in the mouth for 1 month. DIAGNOSIS: The tumor was diagnosed using radiology, pathology, and immunohistochemistry, and it was performed with complete surgical resection. Unfortunately, the tumor recurred 3 months after surgery. INTERVENTIONS: We prescribed metformin for the infant. OUTCOMES: Currently, after 9 months of treatment, the tumor is well controlled without apparent side effects. LESSONS: The case presented suggested that metformin may be an underlying therapy for MNTI.