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HIGH-YIELD FACTS

  • Purpura may be a sign of an underlying life-threatening illness that requires immediate attention.

  • Petechiae above the nipple line with a history of cough or vomiting may be benign and caused by increased venous pressure.

  • Purpura is present in almost all patients with Henoch–Schönlein purpura (HSP), but it may not always be the presenting sign. This can cause a delay in the diagnosis.

  • Consider idiopathic thrombocytopenic purpura (ITP) in a nontoxic-appearing child with absence of splenomegaly and a normal hemoglobin and white blood cell count.

  • Child abuse should be suspected if bruising occurs in non-bony prominences or in areas not normally subjected to injury, or if the history is not consistent with the physical findings.

Purpura results from the extravasation of blood from vasculature into the skin or mucous membranes. A careful evaluation of a patient with a purpuric rash will help differentiate a benign illness from a life-threatening disorder (Fig. 90-1). Although laboratory tests are helpful, a thorough history and physical examination can offer the most information to identify the cause. This chapter provides an overview of the main causes of petechiae and purpura in children.

FIGURE 90-1.

Differential diagnosis of petechiae and purpura.

CAUSES OF PURPURA FULMINANS

Purpura fulminans (PF) is a hematologic emergency characterized by rapid progression of vascular collapse including disseminated intravascular coagulation (DIC), skin necrosis, and multiorgan dysfunction.1 Three forms of this disease have been identified based on the inciting mechanism. Acute infectious PF is the most common form of the disease, and is seen most commonly with severe sepsis during the acute phase of the illness. A hereditary or acquired deficiency of a natural anticoagulant, either protein C or S, or antithrombin III, has been associated with neonatal PF. Idiopathic or postinfectious PF is usually preceded by a benign febrile illness and presents with rapidly progressing purpura which mainly involves the skin and no other organ tissues.2,3

PETECHIAE CAUSED BY INFECTION

PF secondary to sepsis may be a complication of severe bacterial infection, most often gram-negative sepsis, or other infections. The organism most commonly implicated in pediatric patients is Neisseria meningitidis (>90%), followed by Streptococcus pneumoniae and group A and group B streptococci.3,4 Most cases of Staphylococcus aureus sepsis are reported as toxic shock syndrome. Outbreaks occur in semi-closed communities, such as child care centers, college dormitories, and military bases. Transmission occurs by direct contact with secretions or fomites carrying the offending organism.

The sepsis process is initiated by a local intradermal release of endotoxin leading to an inflammatory reaction and increased vascular permeability. The same endotoxin, up to 24 hours later, causes widespread necrotizing vasculitis and microvascular thrombosis by disturbing the anticoagulant and procoagulant pathways, and leading to DIC. There ...

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