Nothing is inside, nor outside, because what is inside is also manifested outside.
Dermatology is intimately linked to internal medicine. As such, there are several ways in which dermatology interacts with general medicine. Because it is the largest organ of the body and is interdependent with all other organ systems, the skin is frequently involved when there is disease in other organs. Cutaneous lesions may occur simultaneously or sequentially with internal disease, and the clinician must learn to observe and act upon cutaneous changes that are present. Therefore, biopsies may be utilized to ascertain the fundamental mechanism of disease or to determine the primary disease process.