Primary Meningeal Melanocytic Tumors Melanocytoma

Melanocytes are normally present in the pia mater and give a dark brown or dusky appearance to the leptomen-inges. Very rarely, the melanocytes undergo tumorous transformation, producing solitary or multiple solid melanocytomas or diffuse leptomeningeal melano-cytosis. The melanocytosis may be associated with cutaneous nevi (neurocutaneous melanosis, Touraine syndrome).

Grossly, the leptomeninges are dark brown or dusky. Histologically, the tumor consists of fusiform or polygonal melanin-containing cells (Fig. 11.31). Malignant transformation with dense cellularity, nuclear pleomorphism, giant cells, and high mitotic activity may also occur.

figure 11.31

Meningeal melanocytosis. Melanin-containing cells infiltrate the leptomeninges and the parenchyma along the Virchow-Robin spaces (HE).

figure 11.31

Meningeal melanocytosis. Melanin-containing cells infiltrate the leptomeninges and the parenchyma along the Virchow-Robin spaces (HE).

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