Neurocutaneous melanosis in a newborn identified prenatally by non-invasive imaging

A 21-year-old pregnant woman (gravida 1 para 1) was referred to the Department of Obstetrics and Perinatology for sonographic examination, which revealed a fetus at 29 + 6 weeks with an irregular cystic-solid subcutaneous mass of heterogeneous echogenicity (16 × 10 × 9 cm in size) covering the surface of both shoulders and the dorsal chest wall (fig. 1). No increase in tumor size was detected up to the delivery.
The neonate was a boy, born in good condition by cesarean section after 39 weeks of gestation. At birth, he was found to have multiple congenital melanocytic nevi. An extensive nevus was noted on the trunk, covering the thorax, loins, buttocks and both thighs, having a circumferential distribution. It was hairy and partially composed of large, elevated tubers (figs. 2, 3).
Because of the suspicion of neurocutaneous melanosis (NCM), the newborn was given an magnetic resonance imaging (MRI) examination which showed the presence of multiple hiperintense lesions, from 3 to 6 mm in diameter, in the cerebellum, medulla oblongata, the enteral part of the pons, left thalamus, calcarine sulcus, and in the parietal-occipital sulcus. Skin biopsy revealed a melanocytic proliferation suggestive of proliferative neurocristic hamartoma as a variant of a congenital melanocytic nevus (figs. 4, 5). In the first dermatoscopy, the features of malignancy were excluded.
In his 22nd month of life, the infant was neurologically asymptomatic, with no signs of epilepsy and generally correct development. A subsequent MRI with contrast revealed mild enlargement of the third and fourth brain ventricles, partial hypoplasia of the lower part of the vermis, other hiperintense lesions in the cortical area, as well as meningeal involvement.
Neurocutaneous melanosis is a rare congenital disorder with a frequency of 1 in 20,000 live births, which is probably caused by improper migration of neural crest cells [1]. Diagnosis of NCM is based on the presence of giant inborn melanocytic nevus (larger than 20 cm for adults and 6–9 cm diameter for newborn patients), or numerous smaller melanocytic lesions accompanied by melanocytic tumors in the central nervous system (CNS). Symptomatic patients (presenting seizures, hydrocephaly or high intracranial pressure), have an enhanced – often fatal – prognosis [2].
The spread of benign or malignant pigment cell tumors of the leptomeninges is observed in NCM, and this determinates the prognosis. Leptomeninges...


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