Histopathological and cellular studies of a case of cutaneous radiation syndrome after accidental chronic exposure to a cesium source

This study was designed for the histopathological, cellular and biochemical characterization of a skin lesion removed surgically from a young male sev eral months after accidental exposure to cesium-137, with an emphasis on ex pression of transforming growth factor beta 1 (TGFB1) and tumor necrosis fa ctor alpha (TNFA) and the occurrence of apoptosis. Under a hypertrophic epi dermis, a highly inhomogeneous inflammatory dermis was observed, together w ith fibroblastic proliferation in necrotic areas. Immunostaining revealed o verexpression of TGFB1 and TNFA inside the keratinocytes of the hypertrophi c epidermis as wed as in the cytoplasm of the fibroblasts and connective ti ssue of the mixed fibrotic and necrotic dermis. Inside this dermis, the TUN EL assay revealed areas containing numerous apoptotic fibroblasts next to a reas of normal viable cells. Overexpression of TGFB1 was found in the condi tioned medium and cellular fractions of both hypertrophic keratinocytes and fibrotic fibroblasts. This overexpression lasted for at least three passag es in tissue culture. The present observations were consistent with the cen tral role of TGFB1 in the determination of chronic radiation-induced damage to the skin and a significant involvement of TNFA. In addition, programmed cell death appeared to take place during the remodeling of the mixed fibro tic and necrotic tissue. (C) 1999 by Radiation Research Society.