Pathological effects of hyperthermia in normal tissues

This is a brief review of the major pathological alterations produced by hyperthermia in normal tissues of humans and other mammals. Whole-body hyperthermia, spontaneous or artificially induced, can produce severe lesions that have been best described in humans: necropsies, of fatal cases of heatstroke or of individuals treated in the 1940s by hyperpyrexia, have demonstrated important lesions in the central nervous system, liver, kidney, heart, adrenal, testis, and bone marrow. All cases have shown hemorrhagic diathesis affecting many tissues, and in some the hemorrhages may have directly contributed to death. The information on the pathology of localized hyperthermia comes mainly from experimental studies in mammals. Pathology descriptions are available mainly for skin, mesenchymal tissues (skeletal muscle and adipose tissue), liver, small intestine, brain, kidney, urinary bladder, prostate, and cartilage. In several of these tissues, however, the morphological data are incomplete, and very few have sequential observations. Thus, the ultimate (delayed) result of the acute lesions of focal hyperthermia is unknown for most tissues. Clearly, more information is needed in order to define the range of safety for clinical hyperthermia.