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Joseph Junewick, MD FACR
over 7 years ago
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Neurocutaneous Melanosis

Case Detail

Anatomy: Brain-Spine
Joseph Junewick, MD FACR
Diagnostic Category: Developmental or Congenital
Created: over 11 years ago
Updated: over 11 years ago
Tags: PEDS
Modality/Study Types: MR
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8 year old female with seizure disorder and large truncal melanotic nevus.

Case Images


Neurocutaneous Melanosis

Clinical Notes

MRI findings are stable dating back to initial post-natal examination.


MR – T1 hyperintensity in the medial temporal lobes, left greater than right, in a perivascular space distribution. No T2 or post-gadolinium abnormalities.


Neurocutaneous melanosis (NCM) is a phakomatosis resulting from dysplasia of the neuroectodermal melanocyte precursor cells, leading to proliferation of melanin producing cells in the skin and leptomeninges. NCM is sporadic, typically affecting caucasians, and thought to be related to deregulation of hepatocyte growth factor/scatter factor.

NCM is associated with other neurocutaneous syndromes and Dandy-Walker malformation. Two theories for the association of NCM with Dandy-Walker malformation include: 1) obstruction of the 4th ventricle by melanocytes, 2) leptomeningeal disease leads to abnormal development of the 4th ventricle, and 3) leptomeningeal melanosis interferes with inductive effects of extracellular matrix, neuronal migration, and formation of CSF pathways.

NCM is different than melanoma of the leptomeninges. The dura is usually spared. Typically the cerebral parenchyma, choroid plexus and ependyma are affected. The parenchymal localization is related to tracking along the meningeal penetration of the perivascular spaces. The amygdala is the most common site of involvement; other sites include the cerebellum, thalami and subfrontal region.

Patients often develop neurological symptoms within 2 years related to increased intracranial pressure and impaired CSF flow and resorption. Other complications include parenchymal hemorrhage, syringomyelia, and spinal arachnoiditis. Approximately 20% of patients have spinal involvement.


Smith AB, Rushing EJ and Smirniotopoulos JG. Pigmented lesions of the central nervous system: Radiologic-pathologic correlation. Radiographics 2009;29:1503-1524.

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