CNS tumor
Meningeal tumors
Melanocytic tumors / melanoma

Author: Jesse Kresak, M.D. (see Authors page)

Revised: 20 April 2017, last major update September 2014

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: melanoma [title] CNS

Cite this page: Melanocytic tumors / melanoma. PathologyOutlines.com website. http://pathologyoutlines.com/topic/cnstumormelanocytictumor.html. Accessed May 29th, 2017.
Definition / general
  • Melanocytes are a normal, yet sparse, cell of the leptomeninges, most often seen over the anterior / lateral cord, brainstem, base of brain
  • Can give rise to rare primary intracranial melanocytic tumors
  • The WHO recognizes three categories of primary CNS melanocytic lesions: diffuse melanocytosis, melanocytoma, malignant melanoma
  • Diffuse melanocytosis: strongly associated with neurocutaneous melanosis, a rare congenital syndrome with giant congenital pigmented skin nevi and high rate of CNS melanoma usually presenting before age 2 (Semin Cutan Med Surg 2004;23:138)
  • Melanocytoma: less than 0.1% of brain tumors, arises at any age
  • Melanoma: incidence of 0.005 cases per 100,000; reported in ages 15 - 71 with a peak in the fourth and fifth decade
Sites
  • Diffuse melanocytosis can involve infra or supratentorial leptomeninges but has highest frequency in cerebellum, brain stem, temporal lobes
    • Involves subarachnoid space and superficial cortex
  • Melanocytomas can occur in any area of meninges; however, have a predilection for cervical and thoracic spinal cord (intradural, extramedullary) and Meckel's cave
  • Melanomas can also occur anywhere within meninges but have predilection for spinal cord, posterior fossa, Meckel's cave
Clinical features
  • Diffuse melanocytosis presents most commonly with features of neurocutaneous melanosis - congenital nevi, hydrocephalus, mass effect and neuropsychiatric symptoms
  • Melanocytoma and melanoma present with mass effect / cord compression symptoms
Radiology images

Images hosted on other servers:

Diffuse melanocytosis

MRI of thoracic area

Abnormal signal in the left temporal lobe

Prognostic factors
  • Diffuse melanocytosis: poor prognosis even when histologically benign
  • Melanocytoma: good prognosis with resection, rarely transforms into malignant melanoma
    • Can be called intermediate grade when Ki67 and mitoses are present but no obvious melanoma
  • Malignant melanoma: poor prognosis (6 years in spine), yet better than metastatic melanoma to CNS (6 months) (J Neurosurg 1987;66:47)
Case reports
Treatment
  • Gross total resection
  • Adjuvant chemoradiation therapy for malignant melanoma
Gross description
  • Usually solitary, well demarcated dural based with black or redish brown discoloration
Microscopic (histologic) description
  • Melanocytoma:
    • Solitary, circumscribed lesions - do not invade adjacent structures
    • Nests (reminiscent of whorls) of relatively uniform cells with variable melanin pigment
    • Bland, oval nuclei with eosinophilic nucleoli
    • Mitoses no more than 1/10 HPF
  • Malignant melanoma:
    • Hypercellular sheets or nests of spindled or epithelioid cells
    • May have significant pleomorphism
    • Atypical mitoses (5/10 HPF)
    • Invasion of adjacent structures or necrosis may be seen
    • Prominent nucleoli
Microscopic (histologic) images

Images hosted on PathOut server:

Images contributed by Dr. Rana Al-Zaidi, King Faisal Hospital, Saudi Arabia

55 year old man with nausea, vomiting and sudden loss of consciousness, and 4 cm temporal lesion - Primary CNS Melanoma



Images contributed by Jesse Kresak, M.D.

Melanocytoma

Melanocytoma: S100

Melanocytoma: MelanA

Melanocytoma: HMB45



Images hosted on other servers:

Melanoma

Melanoma: intraventricular

Melanocytoma

Cytology description

Images hosted on other servers:

Melanoma cells in CSF

Positive stains
Negative stains
Electron microscopy description
  • Melanosomes present, no junctions, no desmosomes
Additional references