Multiple nodular lesions seen in a patient with neurocutaneous melanosis

Neurocutaneous melanosis is a rare congenital syndrome characterized by the presence of large or multiple congenital melanotic nevi and benign or malignant pigment cell tumors of the leptomeninges. A 2-month-old female infant was referred to our department with widespread pigmented nevi, numerous blackish-brown, elevated, firm nodules, eye lesions, temporal bone defect, and generalized convulsion. The sizes of the nodules were from 0.5 to 3 cm; they were either white, black, brown or red, and some of them were eroded and bleeding. Magnetic resonance imaging using gadolinium contrast (MRI-Gd) demonstrated hydrocephalus, defect of the temporal bone, and T1-short and T2-long areas near the cerebrum and the thoracic vertebra (Th 4-5), suggesting the presence of melanosis in the central nervous system. Biopsy specimen of a firm, black nodule of a pigmented lesion on her shoulder revealed sheets of nevomelanocytes in the dermis with a few mitoses and large atypical cells that were positive for HMB-45 and formaldehyde-induced green specific fluorescence. Although this histological architecture is compatible with that of congenital nevi, occasional occurrence of atypical mitoses in the dermis may constitute an early stage of malignant melanoma. To make a definite diagnosis, however, long-time follow-up and repeated skin biopsy are considered necessary.