Introduction of infectious diseases

papules. In the infectious diseases only inflammatory ones occur. They are caused by the proliferation of epidermis and infiltrate development in the papillary layer of derma with vasodilatation and limited edema. Papulas have the same color as roseola and macula. There are papulas of a different size (1-20 mm). Small papulas (1-1.5 mm) are called milliar ones, the larger (2-3 mm) papulars -lenticularis ones. The confluence of separate papules results in the formation of the eruptions elements called plaque.

Erythema - is vast fields of the bloodshot skin which are red, purple-red or magenta. The erythema is formed as a result of large maculae joining. Therefore the erythema has festoon blurry edges. Inside arythmetic fields there can be separate fields of the skin with normal coloring. There is no expressed inflammatory process.

Unlike the infectionists the dermatologists consider that the term "erythema" means inflammatory fields with a diameter from 2 cm up to several dosen centimeters (active erythema), and also cyanosis conditioned by the venous congestion (passive erythema).

Tubercle (tuberculum) — a formation without cavities which arise as a result of the development of an inflammatory infiltrate of granulematous constitution in derma. The hillock differs from a papule, it lies deep in the derma and the infiltrate is determined at the palpation. The hillocks have legible borders and a tendency to grouping. As against papules at further development the hillock can narcotize, forming ulcers and leaving a scar. The hillocks develop in dermal and visceral leishmaniasis, deep mycosis.

Node (nodus) — a limited dense formation with a diameter from 1 up to 5 cm and more that has a spherical or oval form and is situated in the deep layers of derma and hypodermic fat. More often they develop as a result of the inflammatory process.

In some cases they disappear without any traces (nodal erythema), in chronic illnesses they ulcerate and heal leaving a scar.

Wheal (urtica) - an element of an acute inflammatory nature that has no c;vity. There develops an acute restricted edema of the skin papillary layer. It develops owing to the trichangiectasia of the papillary layer of derma, the increase of their penetrability and the outcome of protein-free exudation through a vascular wall, which then compresses the vessels. As a result dense formations of different size and form suddenly develop on the surface of the skin and rise above its level. The cyanolic porcelain-white coloring in the center and the pink-red one on the peripherals are typical. An itch and a burning sensation of the skin appear with the development of a blister. The blisters develop in a serum disease, medicinal allergy and sometimes in some infectious diseases (leptospirosis, virus hepatitis).

Vesicle (vesicula) — a small cavity formation containing serouse, less often serouse-hemorrhagic fluid. The blister develops directly in the false skin, under the keratinous layer, in middle or on border with derma. It rises above the level of the skin as a half-round element with a diameter from 1.5 up to 5 mm. Hereinafter a blister can dry out, forming a semidiaphanous yellowish or brown

Date: 2014-12-21; view: 947