Purpura

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Chapter 37 PURPURA

Theodore X. O’Connell

General Discussion

Purpura is the appearance of red or purple discolorations on the skin, resulting from the extravasation of blood from the vasculature into the skin or mucous membranes. Purpura may be classified according to their size as petechiae (less than 2 mm in diameter), purpura (2 mm to 1 cm in diameter), or ecchymoses (larger than 1 cm in diameter). Purpuric lesions do not blanch with pressure.

Purpura are not dangerous but may be the sign of a serious or life-threatening disorder. Purpura may result from a defect in platelets, plasma coagulation factors, or blood vessels. In general, petechiae and mucosal bleeding result from platelet disorders. Ecchymoses and hemarthrosis usually result from coagulation disorders. Palpable purpura result from vasculitic disorders.

Figure 37-1 provides an algorithm for the diagnosis of purpura in child.

Figure 37-1 Algorithm for the diagnosis of purpura in children. PT, prothrombin time; aPTT, activated partial thromboplastin time.

Medications Associated with Purpura

• Alkylating agents (decreased platelet formation)

• Antimetabolites (decreased platelet formation)

• Anticonvulsants (decreased platelet formation)

• Aspirin (platelet dysfunction)

• Atropine (vascular purpura)

• Chloral hydrate (vascular purpura)

• Chlorothiazide diuretics (decreased platelet formation)

• Cimetidine (immune thrombocytopenia)

• Clofibrate (platelet dysfunction)

• Corticosteroid therapy long term (defective vascular support tissue)

• Estrogens (decreased platelet formation)

• Furosemide (platelet dysfunction)

• Heparin (immune thrombocytopenia, platelet dysfunction)

• Nitrofurantoin (platelet dysfunction)

• Nonsteroidal anti inflammatory drugs (NSAIDs; platelet dysfunction)

• Penicillin (immune thrombocytopenia)

• Quinidine (immune thrombocytopenia)

• Sulfonamides (immune thrombocytopenia)

• Sympathetic blockers (platelet dysfunction)

• Valproic acid (immune thrombocytopenia)

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