Diagnostic Criteria Traditional Diagnostic Criteria Classification Tree
This is a small vessel vasculitis that manifests as abdominal pain, rash, arthralgia, and hematuria. This disorder usually presents with an acute onset and quick resolution after 4 to 6 weeks; however, chronic or recurrent cases do occur. The etiology of this disorder is unknown. Upper respiratory tract infections precede disease occurrence in approximately 90% of cases. While this is characteristically considered a disorder of children, cases do occur in adults, and males are affected twice as frequently as females.
The most sensitive and specific clinical manifestation is the occurrence of palpable purpura located on the extremities and buttocks. This purpuric rash is also located in areas of pressure such as the level of the sock line or around the waist. The rash occurs without concomitant thrombocytopenia. Biopsy of the skin lesions shows a leukocytoclastic vasculitis with deposition of IgA and C3 in the vessel walls. Another cutaneous manifestation of this disorder is regional subcutaneous edema of the extremities, scalp, eyes, or scrotum, which occurs early in the disease course.
Diffuse abdominal pain that is typically postprandial with related bloody diarrhea occurs in 30% of afflicted patients. These gastrointestinal symptoms are believed to be highly specific for Henoch-Schonlein purpura. Gastrointestinal symptoms are believed to be secondary to submucosal and subserosal hemorrhage and the accumulation of fluid in the bowel wall. Intussusception, bowel infarction, and perforation may also occur. Other associated symptoms include oligoarticular synovitis involving four or fewer joints (may be severe and may precede other symptoms by 1 to 2 weeks), diastolic hypertension, and nephritis with associated proteinuria and hematuria. Articular symptoms are transient, nonmigratory, and mainly involve large joints. Joints most frequently affected are the knees and ankles, followed by the elbows and the joints of the hands.
Pulmonary complications are rare but when present manifest as either pulmonary hemorrhage or interstitial disease. The interstitial disease is usually mild and resolves completely. Blood gas values and lung volumes are normal with interstitial lung disease with the only detectable abnormality being a decreased diffusion capacity (DLCO).
When patients present with compatible symptoms, the differential diagnosis includes systemic lupus erythematosus, mixed cryoglobulinemia, meningococcemia, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation, subacute bacterial endocarditis, rickettsial diseases, and Waldenstrom's hyperglobulinemic purpura. Associated laboratory abnormalities are nonspecific and include leukocytosis and a normocytic anemia. Serum antinuclear antibodies and rheumatoid factors are not present. Biopsy of associated skin lesions with the above-mentioned histologic findings may aid in making the diagnosis.
As the disease is usually brief in duration (4 to 6 weeks) with complete resolution (95%) without residual sequelae being the normal outcome, no therapy is usually required. Supportive therapy includes NSAIDs for painful joints, steroids for abdominal pain and in cases of associated renal failure, hemodialysis may be required.