Uncommon type of meningiomas with conspicuous plasmo-lymphocytic infiltration. An immunohistochemical and histochemical study.

Two cases of meningioma revealing conspicuous plasmo-lymphocytic tissue and hyalinized fibrous tissue components are reported. Histopathological examination of the plasmo-lymphocytic infiltration was performed. Both lesions showed polyclonality of plasma cells as revealed by positive reactions for IgG and paraimmunoglobulin kappa- and lambda-light chains, and amyloid infiltration into the fibrous stroma and blood vessel walls. The histochemical and immunohistochemical characteristics of the lesion in relation to its etiology are briefly discussed.