Plasma cell granuloma of the brain.

We describe a 29-year-old woman with a plasma cell granuloma arising in the right superior temporal gyrus. The mass appeared on computed tomography as a well-circumscribed area of increased density that markedly enhanced with administration of contrast. Microscopic examination showed a mixed cell population with a predominance of plasma cells, including plasma cells showing cytologic atypia, as well as necrosis with polymorphonuclear leukocytes, and the tumor was characterized immunohistochemically by polyclonal plasma cell proliferation.