PETECHIAS (petechia, singular; ital. petecchia spot, rash; synonym hemorrhages dot) — a kind of the hemorrhagic spots arising on skin and mucous membranes as a result of the smallest capillary hemorrhages. Items appear in various quantity, as a rule, symmetrically, on any sites of an integument, preferential on an extensor surface of the lower extremities (shins and feet), and also on mucous membranes of an oral cavity, intestines.
Items have rounded shape, the sizes in the diameter of 1 — 5 mm, during the pressing or extension of skin do not disappear. Their color changes from purple-red to cyanotic in the beginning, and then greenish and ocherous.
Items are formed owing to structural changes of a vascular wall, up to development of thrombosis of capillaries, and also as a result of its functional disturbances. P.'s presence — one of characteristic symptoms of the diseases combined by a concept hemorrhagic diathesis (see) which are caused by deficit in blood of the factors necessary for its normal coagulation, reduction of quantity of thrombocytes (an essential thrombopenia, or Verlgof's disease), structural inferiority of a vascular wall (a hemorrhagic vasculitis, or Shenleyn's disease — Genokh), avitaminosis With (scurvy). Items are observed at many inf. diseases (a sapropyra, tick-borne rickettsioses, scarlet fever, diphtheria, a hemorrhagic form of measles, smallpox, hemorrhagic fevers, at a severe form of a viral hepatitis, malaria), hemosideroses of skin, and also at sepsis, hard proceeding pneumonia and rheumatism, a long septic endocarditis, at far come stages of nephrite, obturatsionny jaundice, at a serum disease, a hemorrhagic small tortoiseshell, an acute lupus erythematosus, medicinal intoxications, at impact of ionizing radiation.
Items can be formed as a result of influence of the external factors damaging vessels of skin: a light air (lacunar and high-rise diseases), a pinch, a banner a rubber plait, napr, a shoulder (a so-called bandage sign, or Konchalovsky's phenomenon — Rumpelya — Leede), a sting of insects (fleas, bugs, crab-louses).
Hemorrhagic spots, big in size, than P., usually irregular shape, are called ecchymoses, and spots having the polosovidny form — vibices.
O. K. Shaposhnikov.