Neurocutaneous melanosis (NCM) is known as a rare phakomatose characterised by large or numerous pigmented congenital nevi associated with leptomeninges melanin-containing deposits. We report a case of a newborn presenting at birth with a giant nevus covering about 40% of the total body surface. MRI showed T1 hyperintensities in the right amygdala and predominantly in the cerebellum corresponding to melanocytic cells.
"''Multiple'' is defined as more than three. These specific diagnostic criteria allowed their distinction from CNS metastases of a primary skin melanoma . Figure 1 Revised clinical criteria for neurocutaneous melanosis (NCM) and the more common areas of distribution of the pigmented cutaneous nevi. "
[Show abstract][Hide abstract] ABSTRACT: Neurocutaneous melanosis is a rare, congenital, non-inherited syndrome characterized by numerous and/or large congenital nevi with intracranial leptomeningeal melanocytosis. This report describes two patients, presenting with a giant congenital nevus involving a major portion of the posterior trunk with satellite congenital nevi scattered all over the body, who developed seizures at 4 and 6 months of age, respectively. Changes in follow-up magnetic resonance (MR) examinations over an 8-year period were seen in case 1, while parenchymal melanocytic accumulation was reported in the region of the amygdala in case 2. These cases emphasize that neurocutaneous melanosis should be suspected in patients with giant congenital nevus with or without neurological symptoms. Also, neuroaxial MR screening should be performed in all cases and, ideally, before myelination of the brain to provide the highest sensitivity for detecting melanin deposits in the leptomeninges.
Journal of Neuroradiology 04/2011; 38(5):313-8. DOI:10.1016/j.neurad.2011.02.007 · 1.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Giant congenital melanocytic nevus is usually defined as a melanocytic lesion present at birth that will reach a diameter ≥ 20 cm in adulthood. Its incidence is estimated in <1:20,000 newborns. Despite its rarity, this lesion is important because it may associate with severe complications such as malignant melanoma, affect the central nervous system (neurocutaneous melanosis), and have major psychosocial impact on the patient and his family due to its unsightly appearance. Giant congenital melanocytic nevus generally presents as a brown lesion, with flat or mammilated surface, well-demarcated borders and hypertrichosis. Congenital melanocytic nevus is primarily a clinical diagnosis. However, congenital nevi are histologically distinguished from acquired nevi mainly by their larger size, the spread of the nevus cells to the deep layers of the skin and by their more varied architecture and morphology. Although giant congenital melanocytic nevus is recognized as a risk factor for the development of melanoma, the precise magnitude of this risk is still controversial. The estimated lifetime risk of developing melanoma varies from 5 to 10%. On account of these uncertainties and the size of the lesions, the management of giant congenital melanocytic nevus needs individualization. Treatment may include surgical and non-surgical procedures, psychological intervention and/or clinical follow-up, with special attention to changes in color, texture or on the surface of the lesion. The only absolute indication for surgery in giant congenital melanocytic nevus is the development of a malignant neoplasm on the lesion.
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