purpura n : any of several blood diseases causing subcutaneous bleeding [syn: peliosis]
Purpura (from the Latin, purpura, meaning "purple") is the appearance of red or purple discolorations on the skin, caused by bleeding underneath the skin. Small spots are called petechiae less than 1cm, while large spots are called ecchymoses greater than 1cm.
This is common with typhus and can be present with meningitis caused by meningococcal meningitis or septicaemia.
ClassificationPurpura is a common and unspecific medical sign, however the underlying mechanism commonly involves one of the following:
- Primary thrombocytopenic purpura
- Secondary thrombocytopenic purpura
- Vascular disorders
- Coagulation disorders
- Vitamin C deficiency - defect in collagen synthesis due to lack of hydroxylation of procollagen. It results in weakened capillary walls.
There are also cases of psychogenic purpura described in the medical literature, some claimed to be due to "autoerythrocyte sensitization." Other studies suggest, that local (cutaneous) activity of tPA can be increased in psychogenic purpura, leading to substantial amounts of localized plasmin activity, rapid degradation of fibrin clots, and resultant bleeding. Petechial rash is also characteristic of a rickettsial infection.