Neurocutaneous melanosis and Dandy‐Walker syndrome in an infant

An 18‐week‐old boy was referred by the pediatric service for evaluation of a large congenital nevus. The baby was a term infant who was noted to have extensive pigmented skin lesions at birth that extended from the scalp to the feet. Apgar scores and physical examination (including neuromuscular examination) were within normal limits. Electroencephalographic tracings were normal and unenhanced cranial computerized tomography (CT) was reported as showing a subarachnoid cyst with atrophic changes, involving predominantly the inferior aspect of the cerebellar hemispheres bilaterally. Hydrocephalus or signs thereof were not present. Lumbar spine films were normal. The patient was next evaluated at age 3 months, where he was reported to roll over, reach for objects, and smile. At age 17 weeks, the baby had dermabrasion of an abdominal portion of his congenital nevus, followed by autologous epidermal cell autograft. The baby was subsequently hospitalized at the University of California Irvine Medical Center for complications from this procedure. Upon initial dermatologic evaluation, the baby was noted to have uniformly brown pigmented bathing‐trunk verrucous lesions covering his buttocks, scrotum, two‐thirds of his trunk, and proximal portions of his extremities. Multiple similar but smaller lesions were noted on the face, scalp, and distal extremities (Fig. 1). Tense anterior fontanelles, frontal bossing, Babinski reflexes bilaterally, and possible “setting‐sun” sign (downward gaze of the eyes secondary to pressure from the midbrain) were apparent. Although the length (size) percentile for the baby was normal, the plot of head circumference was noted to deviate above the normal range by age 3 months. Magnetic resonance imaging (MRI) of the brain was performed. The midline sagittal T1 weighted image (Fig. 2a) demonstrated an enlarged posterior fossa with vermin hypoplasia and hydrocephalus. An axial image through the dilated sylvian aqueduct revealed a hyperintense focus, characteristic of melanocytes, adjacent to the dilated left temporal horn (Fig. 2b). More superiorly, enhancing leptomeningeal deposits were identified (not shown). Cerebrospinal fluid was obtained after subsequent placement of a right ventricular‐peritoneal shunt. The fluid was bloody, but sterile, and without malignant cells. Staining for melanin of the few nucleated cells in this limited cerebrospinal fluid sample was negative. Several excisional biopsies of a nevus from locations on the feet, wrist, back, and buttock showed the picture of either congenital melanocytic nevus or congenital melanocytic nevus with atypical melanocytic hyperplasia; however, no significant atypia was identified in the specimens containing foci of atypical melanocytic hyperplasia.