The influence of local hyperthermia on lymphedema and lymphedematous skin of the human leg.

The influence of microwave and hot water immersion hyperthermia on lymphedema and lymphedematous skin of the leg in 12 patients was studied using circumference and volumetric measurements, immunohistochemistry and "quantitative" lymphoscintigraphy. Whereas heating was associated with a reduction in the girth and volume of the leg, lymph flow as assessed by lymphoscintigraphy was unchanged. Neither absorption of the radiolabeled nanocolloid from the injection site nor the rate of tracer accumulation in the inguinal lymph nodes was significantly altered by heat therapy. Histologically, the lymphedematous skin after heat treatment showed near resolution of perivascular cellular infiltration, disappearance of "lymph lakes" and dilatation of blood capillaries. Labeling of skin migrating immune cells with monoclonal antibodies confirmed subsidence of dermal cellular infiltration; nonetheless, there was nonspecific stimulation of resident epidermal immune cells, endothelial cells, macrophages, lymphocytes and keratinocytes by intense expression of class II and other antigens. There seemed to be a direct relationship between the subsidence of dermal inflammation and a decrease in leg edema. We suspect that subsidence of local inflammation in the lymphedematous limb with alteration in the extracellular protein matrix after regional heating accounts for the reduction in peripheral edema.