Thermographic evaluation of the benign diseases and reactive changes of the skin.

White Erythema is combined with an augmentation of heat radiation only if the convection of heat is increased, reflectoric flush phenomenon is detected more reliably by thermography than reflex photometrics. Urticarial exanthema shows an increased heat radiation if the edema derives from the deeper layers of the skin vessels, whereas a cooling effect results from an edema affecting the superficial layers of the skin. Papular lesions with inflammation are characterized by increased heat radiation. Most of the benign skin tumors are not characterized by an increased convection of heat and show approximately the same temperature as the surrounding skin. Diminished heat isolation by atrophy of the subcutaneous fat is followed by an increase of heat radiation by the conduction of heat from the warm inside of the core. The blood storage capacity of the deeper venous plexus and varicose veins of the lower legs maintain a raised skin temperature which can be decreased by pharmacological vasoconstriction of these veins by catecholamines and serotonin. Finally, the pharmacological effectiveness of topically applied drugs can change the blood flow through the skin vessels and alter the heat radiation of the skin surface.