Purpura () is a condition of red or purple discolored spots on the
skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different ...
that do not
blanch on applying pressure. The spots are caused by
bleeding underneath the skin secondary to platelet disorders, vascular disorders, coagulation disorders, or other causes. They measure 3–10 mm, whereas
petechiae measure less than 3 mm, and
ecchymoses greater than 1 cm.
Purpura is common with
typhus and can be present with
meningitis caused by meningococci or
septicaemia. In particular, meningococcus (''
Neisseria meningitidis''), a
Gram-negative
Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...
diplococcus organism, releases endotoxin when it lyses. Endotoxin activates the Hageman factor (clotting factor XII), which causes
disseminated intravascular coagulation (DIC). The DIC is what appears as a rash on the affected individual.
Classification
Purpura are a common and nonspecific medical sign; however, the underlying mechanism commonly involves one of:
*
Platelet disorders (
thrombocytopenic purpura)
**
Primary thrombocytopenic purpura
**Secondary thrombocytopenic purpura
**
Post-transfusion purpura Post-transfusion purpura (PTP) is a delayed adverse reaction to a blood transfusion or platelet transfusion that occurs when the body has produced alloantibodies to the allogeneic transfused platelets' antigens. These alloantibodies destroy the pa ...
*Vascular disorders (
nonthrombocytopenic purpura)
**Microvascular injury, as seen in senile (old age) purpura, when blood vessels are more easily damaged
**
Hypertensive states
**Deficient vascular support
**
Vasculitis, as in the case of
Henoch–Schönlein purpura
Henoch–Schönlein purpura (HSP), also known as IgA vasculitis, is a disease of the skin, mucous membranes, and sometimes other organs that most commonly affects children. In the skin, the disease causes palpable purpura (small, raised areas of b ...
*
Coagulation disorders
**
Disseminated intravascular coagulation (DIC)
**
Scurvy
Scurvy is a deficiency disease, disease resulting from a lack of vitamin C (ascorbic acid). Early symptoms of deficiency include weakness, feeling tired and sore arms and legs. Without treatment, anemia, decreased red blood cells, gum disease, ch ...
(
vitamin C deficiency) – defect in collagen synthesis due to lack of hydroxylation of procollagen results in weakened capillary walls and cells
*
Meningococcemia
Meningococcal disease describes infections caused by the bacterium ''Neisseria meningitidis'' (also termed meningococcus). It has a high mortality rate if untreated but is vaccine-preventable. While best known as a cause of meningitis, it can al ...
*Clumping
fibril
Fibrils (from the Latin ''fibra'') are structural biological materials found in nearly all living organisms. Not to be confused with fibers or filaments, fibrils tend to have diameters ranging from 10-100 nanometers (whereas fibers are micro ...
lary protein deposits caused by
Amyloidosis
*
Cocaine
Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Am ...
use with concomitant use of the one-time chemotherapy drug and now veterinary deworming agent
levamisole can cause purpura of the ears, face, trunk, or extremities, sometimes needing
reconstructive surgery.
Levamisole is purportedly a common cutting agent.
*Decomposition of blood vessels including purpura is a symptom of acute
radiation poisoning in excess of 2
Grays of radiation exposure. This is an uncommon cause in general, but is commonly seen in victims of nuclear disaster.
Cases of
psychogenic purpura are also described in the medical literature,
some claimed to be due to "autoerythrocyte sensitization". Other studies
suggest the local (cutaneous) activity of
tissue plasminogen activator 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
''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "ricket ...
infection.
Etymology and pronunciation
The word ''purpura'' () comes from Latin ''purpura'', "
purple
Purple is any of a variety of colors with hue between red and blue. In the RGB color model used in computer and television screens, purples are produced by mixing red and blue light. In the RYB color model historically used by painters ...
", which came from ancient Greek πορφύρα. ''Purpura'' is a
mass noun naming the condition or state, not the name of an individual spot (thus there is no *''pupurum'', *''purpura'' or *''purpura'', *''purpurae'' count declension).
See also
*
Bruise, which is a hematoma caused by trauma
*
Petechia, which is a small type of hematoma (<3 mm)
*
Ecchymosis, which is a large type of hematoma (>1 cm)
*
Purpura secondary to clotting disorders
*
Purpura hemorrhagica in horses
*
Pigmented purpuric dermatosis
*
Schamberg disease
Schamberg's disease, (also known as "progressive pigmentary dermatosis of Schamberg", "purpura pigmentosa progressiva" (PPP), and "Schamberg's purpura") is a chronic discoloration of the skin found in people of all ages, usually only affecting ...
(progressive pigmentary purpura)
References
External links
Evaluating the Child with Purpura from
American Academy of Family Physicians
{{Authority control
Dermatologic terminology
Medical signs