Meningeal melanoma

Case contributed by Dr Mahesh Gautam

Presentation

Occasional headache for 3 months.

Patient Data

Age: 55 years
Gender: Female
MRI

MRI brain demonstrates extra-axial mass in left posterior parasagittal region. The mass displays variable signal on T1WI. Most of the mass is isointense to gray matter and its peripheral portion hyperintense. On T2WI/FLAIR the lesion is isointense to gray matter with a peripheral hypointense rim. The peripheral rim shows blooming on SWI, suggesting blood products. The lesion enhances avidly and homogeneously after IV contrast administration. No diffusion restriction. Perilesional white matter edema with compression of the posterior third of the body of corpus callosum.

Bilateral punctate-to-confluent areas of T2WI/FLAIR hyperintensity in deep white matter of fronto-parietal lobes.

The patient proceeded to craniotomy with resection of the mass. A highly vascular, blackish mass adherent to the arachnoid membrane and the parasagittal cortex was removed.

Pathology

Section examined shows solid sheets of tumor cells arranged in vague fasciles and irregular islands with large areas of hemorrhage in between. The tumor cells are spindle to epithelioid with high nucleo-cytoplasmic ratio, coarse chromatin and prominent eosinophilic nucleoli. Many of these tumor cells shows abundant dark brown melanin pigments in their cytoplasm. Brisk atypical mitosis is also noted. 

Features are of melanoma and could represent a primary meningeal melanoma or metastatic melanoma from other primary site.

Case Discussion

Meningeal melanoma is a primary CNS tumor arising from melanocytes of the leptomeninges derived from neural crest cells.1 They can occur in any age group. Most commonly they have a predilection for the posterior fossa and spinal cord and commonly present as a solitary mass.

 

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