Neurocutaneous Melanocytosis: Case Report of a Catastrophic Evolution

Case presentation: A 2-year-old boy with Dandy-Walker syndrome diagnosed by obstetric ultrasound, presented diffuse and large nevi at birth. He was submitted to endoscopic third ventriculostomy at 15 days old due to obstructive hydrocephalus. Spinal fluid was then sent for analysis but showed no melanocytes. MRI of the brain showed no additional findings and mutation analysis could not be performed. After 1 month he needed a ventriculoperitoneal shunt. During the COVID-19 pandemic, he lost follow-up care until presenting at the emergency room with decreased level of consciousness, respiratory distress and flaccid paraparesis at 21 months of age. A new MRI revealed a hyperintense signal which characterized an expansive lesion embracing the bulb and obliterating the great cistern on T2 weighted images. A biopsy was performed showing leptomeningeal melanoma, therefore, confirming the diagnosis of neurocutaneous melanocytosis (NCM). As there were no available curative options, a palliative extubation was performed.

Discussion: Described in 1861 by Rokitansky and named by Van Bogaert in 1948, NCM is a rare sporadic congenital syndrome with only around 300 cases reported in literature. It is characterized by large (≥ 20 cm in adults, ≥9 cm on an infants’ head, or ≥ 6 cm on an infants’ body) or multiple (≥ 3) congenital melanocytic nevi in association with melanocytes proliferation in the leptomeninges and brain parenchyma. Approximately 80% of NCM have a single mutation in codon 61 of NRAS. It has an elevated morbimortality due to increased risk of intracranial hypertension secondary to obstruction and malignization of melanocytes lesions. Association with CNS malformations is common, particularly the Dandy-Walker complex. Until now, there is no specific treatment for this disease, although early diagnosis assures a better multidisciplinary approach and prompt treatment of complications.

Final comments: Our case illustrates a fast and tragic evolution of NCM. It sheds light on the need of a high level of surveillance for complications, therefore demanding serial neuroimages. Despite the severity, we now have reached a better rate of survival when compared with older series reports that showed mortality as high as 98 per cent. Advances in oncology and surgical fields are cardinal for this paradigm shift. Therefore, early diagnosis and multidisciplinary approach are essential.

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Artikel online veröffentlicht:
18. September 2023