Neurocutaneous melanosis and the Dandy–Walker complex: an uncommon but not so insignificant association

Abstract

Neurocutaneous melanosis is considered to follow from neurulation disorders which could account for associated developmental malformations as the so-called Dandy-Walker complex. Cutaneous lesions are usually recognized at birth whereas neurological manifestations develop later. Numerous neurological symptoms have been reported according to extent of leptomeningeal and parenchymal infiltration. Whether magnetic resonance imaging of the neuroaxis represents the choice radiological exam, definite diagnosis relies upon the histological data obtained by mean of biopsy. Once symptomatic, surgical and medical measures remain palliative since death occurs within 3 years.

Dandy-Walker Malformation Associated with Neurocutaneous Melanosis

“…Although the pathogenesis of neurocutaneous melanosis has not been elucidated, theories focus on defective morphogenesis of the neural ectoderm in the developing embryo [1][2][3][4][5]8,[10][11][12][13][14][15] . Melanocytes of the skin and pia mater are believed to be derived from multipotential precursor cells of the neural crest.…”

“…Whether the ventricular outlet is obstructed or not, the dysgenesis of the cerebellum and fourth ventricle may result in the gradual accumulation of CSF in the posterior fossa, but still allow absorption in a critical equilibrium because of the relatively high-pressure gradient between the CSF pathway and the venous compartment. The physiological increase in systemic blood pressure after birth results in a decreased pressure gradient and a disruption of the absorption of CSF, leading to hydrocephalus [1][2][3][4][5]7,[10][11][12][13][14]18,19) . At least 100 cases of neurocutaneous melanosis have been reported; in 15 cases, there were associations between DandyWalker malformation and neurocutaneous melanosis [1][2][3][4][10][11][12][13][14][15][16]18,19) .…”

“…The common neurological manifestations of these two abnormalities are irritability, seizures, lethargy, nausea and vomiting, neck stiffness, bulged fontanels, papilledema, and cranial nerve palsies, which are the signs and symptoms of increased intracranial pressure. Once the neurological symptoms manifest, the course is usually progressive and fatal due to primary CNS melanosis 1,3,5,10,12,[14][15][16] . The association of Dandy-Walker malformation with neurocutaneous melanosis seems to have an extremely poor prognosis.…”

“…In all reported cases, the patients showed rapid neurological deterioration and death by four years of age. The presence of these two abnormalities represents a phenotypic marker for more profound melanotic infiltration of the leptomeninges, which increases the risk of malignant transformation 4,12) . The characteristic MRI findings are severe cerebellar vermian mable valve) (Fig.…”

Course Peculiarities of Neurocutaneous Melanosis in Children

“…Известно, что меланоциты кожи и мягкой мозго-вой оболочки являются производными мультипотент-ных клеток нервного гребня [5]. Вследствие дисплазии меланоцитнейроэктодермальных клеток-предшествен-ников возникает быстрое распространение меланин-продуцирующих клеток в коже и мягкой мозговой обо-Клиническое наблюдение лочке с морфологическим формированием диффузного лептоменингеального меланоцитоза и обширным рас-пространением изначально незлокачественных клеток на мозговые оболочки [4,6,7]. Риск малигнизации (трансформация доброкачественных клеток в злокаче-ственные) при таком процессе достигает 40-60% [8,9].…”