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

Blood spots; Skin hemorrhages

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.

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

Nonthrombocytopenic purpuras may be due to:

• Congenital cytomegalovirus
• Congenital rubella syndrome
• Drugs that affect platelet function
• Fragile blood vessels (senile purpura)
• Pressure changes that occur during vaginal childbirth
• Inflammation of the blood vessels (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

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.