ABSTRACT
The oldest form of medical diagnosis is the direct visual observation of the patient’s skin, tongue, eyes and mucous membranes. Health care providers in the millennia before antibiotics were adept at diagnosing local infections, such as those that might have resulted from cuts, abrasions, contusions (bruises), etc., as well as bacterial skin infections such as furuncles and carbuncles. Swelling, skin color, and local heat are external signs of subcutaneous inflammation, which can be caused by bacterial infection, insect bites, or allergy. A fulminating tissue infection can be fatal if the pathogen spreads and attacks organs such as the heart, lungs, kidneys, or brain. A localized or compartmented infection can produce pus, and, in extreme cases, if the pathogen is anaerobic, gas (H
, N
). Malignant melanoma skin lesions are identified by size, color and texture.
