Paraneoplastic syndrome in the course of lung adenocarcinoma: morphological picture and immunohistochemical analysis of the inflammatory infiltrates and PECAM-1 expression.

We examined sections of brain, spinal cord, spinal roots, and peripheral nerves from a patient with paraneoplastic syndrome in the course of lung adenocarcinoma. Morphological examination showed marked loss of myelin fibers in peripheral nerves, severe brain tissue edema, and paraneoplastic degeneration involving cerebrum and cerebellum with inflammatory components. Inflammatory infiltrates examined immunohistochemically using antibodies against antigens CD 3, CD 4, CD 8, and CD 20 turned out to be composed of cytotoxic T lymphocytes. The expression of platelet-endothelial cell adhesion molecule-1 (PECAM-1) in blood vessels was increased in comparison with control material, which may facilitate transendothelial lymphocyte migration triggering a cascade of biochemical and morphological reactions observed in paraneoplastic syndrome.