PRIMARY BALLOON CELL MALIGNANT-MELANOMA OF THE RIGHT TEMPORO-PARIETALREGION ARISING FROM MENINGEAL NEVUS

An unusual case of primary balloon cell malignant melanoma (BCMM) in b rain arising from melanoblastic meningeal (or diffuse meningeal) naevu s in a 30-year-old woman has been presented. The characteristic balloo n cells were amelanotic or focally extremely weakly melanotic. The lar ge, uniformly looking, tightly packed, pale ''balloon cells'' formed t he homomorphic texture of the spherical well demarcated tumor lying in the white matter of right temporo-parietal region beneath the nevoid- looking partially melanotic diffuse meningeal and cortical infiltrate. Positive melanoma antigen HMB-45, S-100 protein and vimentin along wi th negative epithelial membrane antigen EMA and markers for macrophage s like alfa-1-antitrypsine and CD-68 proved that balloon cells belong to and may form a peculiar type of melanoma. The lack of suspected ski n or mucosal naevi and coexisting meningeal naevus speak for the prima ry character of the balloon cell melanoma. According to our knowledge it is the first primary balloon cell melanoma of the brain. Differenti al diagnosis and the pathogenesis are discussed.