A prodromal event can often be identified in the preceding weeks prior to the onset of symptoms. The diagnosis of HSP is made when there are petechiae or purpuras and at least one of the following: arthritis or arthralgias, abdominal pain, histopathology demonstrating IgA deposition, or renal involvement.4 Cutaneous involvement occurs in 100% of cases and includes 1 to 10 mm palpable purpuric lesions and pinpoint petechiae distributed symmetrically over the lower extremities (Fig. 89-3 A) and buttock region (Fig. 89-3B). Though the purpuric lesions are usually concentrated over the lower half of the body, they are not restricted to those areas. These purpura are unrelated to any underlying coagulopathy. Occasionally, the systemic symptoms occur before the lesions appear which can cause a delay in diagnosis. Joint involvement and/or abdominal pain develops before the rash in 30% to 43% of patients.4
A. Henoch–Schoenlein purpura on lower extremities. B. Henoch–Schoenlein purpura on buttocks.
Joint manifestations are the second most common feature of HSP and can be seen in up to 80% of patients. The vasculitis typically causes arthralgia and arthritis of the knees and ankles. The involvement may be so severe that it may restrict walking. Arthritis may precede the onset of cutaneous symptoms by a week in 15% to 25% of patients.5
Renal involvement is common and can be seen in up to 60% of children with HSP.6 Symptoms can manifest from a few days to 4 weeks after the onset of other symptoms. Although most patients have asymptomatic microscopic hematuria with or without proteinuria, some may present with an acute nephritis or nephrotic syndrome. Patients with microscopic hematuria and minor proteinuria have an excellent prognosis, whereas 20% to 40% of those with nephritis complicated by nephrotic syndrome, experience long-term renal involvement.5 Of the patients who develop HSP nephritis, 1% to 7% will likely advance to end-stage renal disease.5 Another genitourinary complication that should be considered is orchitis. Approximately 27% of males with HSP will present with testicular pain mimicking torsion.4 Testicular torsion, though unlikely, should still be considered.
Abdominal pain is the most common gastrointestinal symptom; however, patients may also complain of vomiting, hematemesis, and bloody stools. Gastrointestinal symptoms may precede purpura by up to 2 weeks.4 The abdominal pain may be severe, but usually does not last for more than 24 hours. The stool can have either occult or gross blood. Intussusception is a well-recognized but rare complication of HSP, occurring in up to 5% of patients.4 Pancreatitis, hydrops of the gallbladder, and protein-losing enteropathy are also recognized but rare features. Rarely, there can be cerebral involvement causing seizures or intracranial hemorrhage.4,6
There are no specific diagnostic tests for HSP; however, certain laboratory findings will aid in the diagnosis and help identify specific organ system involvement. A complete blood count will reveal whether or not the cutaneous lesions are secondary to thrombocytopenia. In HSP, platelet counts are normal. A complete metabolic profile may demonstrate renal function involvement with an elevated creatinine and low albumin.4 A urine analysis with microscopy will show the extent of renal involvement. Serum C3 and C4 concentrations are low in a few patients. Stool guaiac will help to identify the presence of gastrointestinal bleeding. Other laboratory and radiographic studies are useful to exclude other conditions that may be associated or mimic HSP before the purpuric lesions appear (i.e., septic joint, intussusception, appendicitis, testicular torsion).
HSP is usually a self-limited condition. Supportive care, such as analgesia, is required for patients with skin involvement only. There is no evidence to support the use of nonsteroidal anti-inflammatory drugs (NSAIDs) in the treatment of HSP.6 The use of NSAIDs and the impact on renal disease in HSP have not been determined.5 For the majority of cases, treatment and follow-up can be done on an outpatient basis.
Inpatient therapy may be warranted in the presence of internal organ involvement. Hospital admission should be considered for children with significant joint pain that precludes walking or significant abdominal pain that precludes eating. Pulse therapy with intravenous corticosteroids may be beneficial for children with significant joint or abdominal pain. Early treatment with steroids has been associated with resolution of abdominal pain within 24 hours, and a reduction in the development of persistent renal disease.6,7 The use of plasmapheresis, immunosuppressive agents and intravenous immunoglobulin therapy may be of benefit when used in conjunction with corticosteroids for the more severe forms of nephritis.4