Immunopathological significance of IgG in meningioma in relation to the pseudopsammoma bodies.

We described two histochemical patterns of IgG deposits in meningioma and discussed the pathogenesis of IgG deposits. In meningioma with pseudopsammoma bodies, IgG was secreted from tumour cells which differentiated to secretory epithelial cells, and was found to deposit in the pseudopsammoma bodies. However, in meningioma without pseudopsammoma bodies, IgG was derived from plasma and became deposit around the blood vessels in the meningioma tissue.