Neurocutaneous melanosis

Neurocutaneous melanosis, or neurocutaneous melanomatosis, is a rare sporadic phakomatosis characterised by dermal and meningeal melanocytosis/meningeal melanomatosis

The disease is characterised by melanotic naevi in skin. The diagnosis is often made in the first few years of life when the child presents with hydrocephalus due to meningeal melanocytosis/meningeal melanomatosis (aka diffuse melanosis) 5

Diagnostic features have been proposed 2:

  1. unduly large or unusually numerous pigmented nevi in association with leptomeningeal melanosis or melanoma
  2. no evidence of malignant change in any of the cutaneous lesions
  3. no evidence of malignant melanoma in any organ apart from the meninges

It is believed that neurocutaneous melanosis is the result of congenital dysplasia of melanoblasts (melanocyte precursors) which are of neural crest cells origin. These are located in the leptomeninges, globes, inner ear, sinonasal cavity and skin 1,4

For leptomeningeal imaging features, please refer to meningeal melanocytosis.

In addition to or instead of leptomeningeal involvement, parenchymal changes are seen in some individuals characterised by T1 signal hyperintensity involving the mesial temporal lobes (particularly the amygdala), ventral pons and medulla  6.

Dandy-Walker malformation is also not infrequently identified 6,7

Prognosis in symptomatic cases is extremely poor, even in the absence of malignant transformations.

Malignant transformation of cutaneous naevi is variably reported from 2-13% 4

Malignant transformation of CNS melanosis occurs very frequently, in up to 50% 5.

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Article Information

rID: 25472
Section: Syndromes
Tag: cases
Synonyms or Alternate Spellings:
  • Neurocutaneous melanomatosis

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