Lesions
Primary lesions
Macule: A macule is a change in surface color, without elevation or depression, so nonpalpable, well or ill-defined, variously sized, but generally considered less than either 5 or 10 mm in diameter at the widest point. Patch: A patch is a large macule equal to or greater than either 5 or 10 mm across, depending on ones definition of a macule. Patches may have some subtle surface change, such as a fine scale or wrinkling, but although the consistency of the surface is changed, the lesion itself is not palpable. Papule: A papule is a circumscribed, solid elevation of skin, varying in size from less than either 5 or 10 mm in diameter at the widest point. Plaque: A plaque has been described as a broad papule, or confluence of papules equal to or greater than 10 mm, or alternatively as an elevated, plateau-like lesion that is greater in its diameter than in its depth. Nodule: A nodule is morphologically similar to a papule in that it is also a palpable spherical lesion less than 10 mm in diameter. However, it is differentiated by being centered deeper in the dermis or subcutis. Tumor: Similar to a nodule, but it is larger than 10 mm in diameter. Vesicle: A vesicle is a small blister, a circumscribed, epidermal elevation generally considered less than either 5 or 10 mm in diameter at the widest point.
Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source. Diseases of the skin
Diseases of the skin include skin infections and skin neoplasms (including skin cancer). History
In 1572, Geronimo Mercuriali of Forlì, Italy, completed De morbis cutaneis (On the diseases of the skin). It is considered the first scientific work dedicated to dermatology. Diagnoses
The physical examination of the skin and its appendages, as well as the mucous membranes, forms the cornerstone of an accurate diagnosis of cutaneous conditions. Most of these conditions present with cutaneous surface changes termed "lesions," which have more or less distinct characteristics. Often proper examination will lead the physician to obtain appropriate historical information and/or laboratory tests that are able to confirm the diagnosis. Upon examination, the important clinical observations are the (1) morphology, (2) configuration, and (3) distribution of the lesion(s). With regard to morphology, the initial lesion that characterizes a condition is known as the "primary lesion", and identification of such a lesions is the most important aspect of the cutaneous examination. Over time, these primary lesions may continue to develop or be modified by regression or trauma, producing "secondary lesions". However, with that being stated, the lack of standardization of basic dermatologic terminology has been one of the principal barriers to successful communication among physicians in describing cutaneous findings. Nevertheless, there are some commonly accepted terms used to describe the macroscopic morphology, configuration, and distribution of skin lesions, which are listed below.