Clinical/Scientific Notes

Case report. A 12-year-old boy with multiple nevi presented with 6 months of polydipsia ( 4 L/day), polyuria, and a 40-pound weight loss that progressed over weeks to intractable headache and vomiting. The patient subsequently developed ataxia, complex partial seizures, and encephalopathy. Medical history was significant for numerous (40 to 50) benign congenital nevi ranging in diameter from 1 to 10 cm. He did not have a previous diagnosis of neurocutaneous melanosis (NCM) or a history of CNS disease. The initial workup revealed hyperglycemia (random blood glucose of 400) and hemoglobin (Hgb) A1c 11.9%. Anti–glutamic acid decarboxylase (GAD) antibody was 2.1 U/mL (normal 0.1). There was diffuse leptomeningeal enhancement on MRI. Initial lumbar puncture revealed an opening pressure of 40 cm H2O, white blood cell count of 23, glucose 40, and protein 193. Cytology from the CSF demonstrated atypical melanocytes consistent with malignant melanoma (figure). EEG showed epileptiform activity in the right mid-temporal cortex. Dermatologic evaluation of the congenital nevi revealed stable lesions without evidence of malignant transformation. The presence of CNS melanoma and numerous congenital melanocytic nevi confirmed the diagnosis of NCM. The patient was treated with wholebrain radiation, interferon, temozolamide, diamox, and phenytoin. He had a peak insulin requirement of insulin glargine 15 units qhs and insulin aspart ac. Repeat serum evaluation revealed blood glucose of 90, HgbA1C 5.3%, and undetectable anti-GAD antibody ( 0.1). His headache and tremor resolved without recurrence. He had a breakthrough seizure that prompted the addition of levetiracetam. After 6 months of diabetes mellitus (DM) management, our patient no longer required insulin to maintain normoglycemia. The skin lesions remained stable throughout the course of his disease without evidence of malignant transformation. Our patient never demonstrated evidence of spread of his melanoma beyond the CNS. The patient subsequently developed progressive cachexia, a large midline cerebral mass, and left-sided hemiparesis with increased seizure activity. He died 14 months after the start of therapy.