Primary morphological elements of the skin
1. Spot - a limited discoloration of the skin and oral mucosa. They can be of various sizes, shapes and colors. According to the mechanism of occurrence, vascular and dyschromic spots are distinguished.
Vascular spots: a consequence of temporary or persistent vasodilation as a result of inflammation or a violation of the integrity of the vascular wall. Multiple, up to 2 cm in diameter, are called roseola, larger - erythema. Roseola is usually observed in patients with allergic dermatitis, toxidermia, pink lichen, pityriasis versicolor, secondary syphilis. Roseolous rashes also occur in infectious diseases in children (measles, rubella, scarlet fever) and in adults with paratyphoid fever, mononucleosis, etc. Erythematous spots are prone to fusion, have irregular outlines, clear boundaries, are often combined with swelling of the skin and are accompanied by intense itching. They are formed in patients with dermatitis, eczema, erythema multiforme exudative.
Hemorrhagic vascular spots (purpura) on the skin and mucous membranes appear as a result of hemorrhage in the epidermis or papillary dermis (rupture or increased vascular permeability). The color of such spots, which do not disappear when pressure is applied to them, depends on the time of their existence: from red to brown. Single hemorrhagic spots up to 1 cm in diameter are called petechiae, large ones are called ecchymoses, and large bruises
- hematomas. Hemorrhagic spots are observed in patients with vasculitis, toxidermia, and with infectious diseases (typhus, typhoid fever, measles, diphtheria, etc.).
Dyschromic spots occur due to excessive deposition of pigment in the skin (hyperpigmentation) or, conversely, when it disappears (depigmentation). Hyperpigmentation can be congenital (nevus) and acquired, for example, freckles, chloasma during pregnancy. Depigmentation can also be congenital (albinism) and acquired (vitiligo, secondary syphilis, typhus and typhoid fever, etc.).
2. Nodule - limited compaction, usually somewhat elevated above the surface of the skin, is determined by feeling. The nodules are flat, cone-shaped or hemispherical and pointed in shape. The outlines are different, the color is from reddish brown to grayish yellow or normal skin. The surface of the nodule can be smooth, shiny or covered with a copious amount of scales. The value is from millet grain (diameter 1 mm) to the size of a coin (2.5 cm in diameter). In a number of diseases, such as psoriasis, nodules fuse together, forming plaques. Nodular elements are characteristic of lichen planus, psoriasis, secondary syphilis. There may also be patients with tick-borne relapsing fever and with infection caused by the human immunodeficiency virus.
3. Tubercle - outwardly similar to a nodule, but differs in a deep location in the skin and in that it always leaves a scar when it disappears. They occur with skin tuberculosis, leprosy, leishmaniasis, tertiary syphilis.
4. Node - embedded in subcutaneous fat. Increasing in size (up to 5 cm or more), it is soldered to the skin, softening appears in the center of the seal, then an ulcer that heals with a scar. The formation of nodes can be a consequence of the inflammatory process, tumor growth (including malignant) and the result of deposition of calcium and cholesterol salts in the skin.
5 Blister is a swelling of the skin with intense itching, resulting from acute limited swelling of the dermis. An example is a nettle burn or mosquito bite. Holding out for several hours (even minutes), the blisters disappear. A rash with the formation of large areas with a significant number of scratches occurs with urticaria, anaphylactic reactions, as well as with some infectious diseases - viral hepatitis, soda, etc.
6. Bubble - a cavity element filled with serous transparent contents. It rises domed above the skin and has dimensions from 1 mm to 0.5 cm in diameter.
A bubble is a larger element. Its contents may be transparent, cloudy or hemorrhagic. They occur both on the appearance of unchanged skin and on the background of an edematous erythematous spot in patients with pemphigus, herpetiform dermatosis, and herpes. Quite often observed in infectious diseases: chickenpox, scarlet fever, malaria, dysentery, etc. Subsequently, the bubbles and bubbles either dry out and turn into crusts, or burst and erosion forms in their place.
7, Pustules - a cavity element with purulent contents, protruding above the surrounding skin in the form of a hemispherical formation. It is formed as a result of death (necrosis) of epithelial cells under the influence of various pyogenic microorganisms. Purulent inflammation can occur in the hair follicle (folliculitis), then hair sticks out in the center of the abscess. When pustules are localized in the epidermis, which does not affect the hair follicle, a bubble with a flabby thin cover and serous contents is visible on the skin surface. This variety of abscess is called conflicts.