Psoriasis, like other skin diseases, is diagnosed by a dermatologist . Most often, a visual examination is enough to make a diagnosis of plaque -like (the most common type) psoriasis. At the first stage, a rash appears in the form of papules of various sizes. Close to each other, they coalesce to form psoriatic plaques , which have a clear border and a rich, hot pink color. In addition, the plaques are covered with a white, gray or yellowish coating – scales that easily peel off when scratched.
Thus, psoriasis is characterized by the presence of the ” psoriatic triad” – pinpoint bleeding, a symptom of a stearin stain and a terminal film. Stearin stain is easily removable scales on the surface of the plaque. The spot is formed due to the accumulation of air bubbles in the stratum corneum of the skin and increased lipid secretion. Intercellular connections are weakened, the stratum corneum does not receive nutrition, the cells die. Terminal film – the affected area, represented by thin, inflamed skin under a stearin stain. The film is wet and shiny, very thin and easily damaged. It contains many capillaries that expand during the inflammatory process. They are easily damaged by tearing off the terminal film. A lot of droplets of blood will come out on the surface – that same pinpoint bleeding .
Psoriasis can affect any part of the body, including the palmar-plantar surfaces and the scalp, depending on the type of disease.
However, in some cases, psoriasis can be confused with dermatitis or eczema. In this case, examination alone is not enough, a skin biopsy and a blood test are necessary. In blood tests for psoriasis, an increased level of leukocytes, proteins and a high erythrocyte sedimentation rate are found.
Since psoriasis is autoimmune in nature, histological analysis of the skin should not show the presence of microorganisms (for example, seborrheic dermatitis is characterized by the presence of Malassezia fungi furfur ). In addition, a biopsy of skin affected by psoriasis reveals an accumulation of so-called Rete bodies , thickening of the stratum corneum of the epidermis, accelerated formation of blood vessels in the skin under the plaque, immaturity of young skin cells, and the absence of a granular layer of the skin.
Also, with a progressive (acute) stage of psoriasis, a symptom of Koebner is observed. – the appearance of new papules at the site of skin damage: cut, burn, injection, etc.
In addition to the progressive, 2 more stages of the development of psoriasis are distinguished. At the stationary stage , the appearance of new plaques stops and existing plaques stop growing. The regressing stage is characterized by discoloration of plaques, their flattening, and the elimination of peeling. Hypo- or hyperpigmentation is often observed in the area of previous rashes.