Purpura

Definition

Purpura is purple-colored spots and patches that occur on the skin, on organs, and in mucous membranes, including the lining of the mouth.

Alternative Names

Considerations

Purpura occurs when small blood vessels under the skin leak.

When purpura spots are very small, they are called petechiae. Large purpura are called ecchymoses.

A person with purpura may have normal platelet counts (nonthrombocytopenic purpuras) or decreased platelet counts (thrombocytopenic purpuras). Platelets help the blood clot.

Causes

Nonthrombocytopenic purpuras may be due to:

• Drugs that affect platelet function
• Congenital cytomegalovirus
• Congenital rubella syndrome
• Fragile blood vessels (senile purpura)
• Pressure changes that occur during vaginal childbirth
• Vasculitis such as Henoch-Schonlein purpura

Thrombocytopenic purpura may be due to:

• Drugs that prevent platelets from forming
• Hemangioma
• Idiopathic thrombocytopenic purpura (ITP)
• Immune neonatal thrombocytopenia (can occur in infants whose mothers have ITP)
• Meningococcemia

References

Goldman L, Ausiello D. Cecil Textbook of Medicine. 22nd ed. Philadelphia, Pa: WB Saunders; 2004:2410.

Hoffman R, Benz EJ, Shattil SS, et al. Hematology: Basic Principles and Practice. 4th ed. Orlando, Fl: Churchill Livingstone; 2005.