CLINICAL FEATURES AND COMPLICATIONS
The diagnosis of HSP is clinical and based on palpable purpura along with one of the following features:
1. Diffuse abdominal pain;
2. Arthralgia or acute arthritis;
3. Renal involvement with proteinuria or hematuria; or
4. Renal biopsy with predominant IgA deposition with leukoclastic vasculitis.
Skin rash in HSP has been described as petechial or palpable purpura. The rash is symmetrical, nontender, and most commonly observed on the extensor surfaces of the dependent portions of the lower extremities and the buttocks. Involvement of the abdomen and face have been described in rare cases.6 Hemorrhagic bullae have been reported in only 2% of the affected children and are not related to the severity or the progression to renal failure.7 In some cases, macular and urticarial rashes have been reported prior to the development of the purpuric rash.6
Abdominal pain is the most common (~75%) associated symptom secondary to visceral purpura causing bowel edema and hemorrhage. Colicky diffuse pain, which is worse after meals and that may be associated with emesis, hematemesis, or guaiac positive stool, is the most common presentation. Although it is associated with purpura the majority of the time, abdominal pain may precede the classic rash in less than 40% of the cases, thereby making the diagnosis a challenge.8 Intussusception is the most common complication of abdominal involvement, and an ultrasound is the initial diagnostic modality for identifying it. More severe complications such as extensive hemorrhage and bowel wall gangrene are rare.
Arthritis/arthralgia is the presenting symptom in approximately 25% of patients with HSP, however, more than 50% of patients have articular involvement.5,9 It is usually oligoarticular and involves the larger joints of the lower extremities. Even though the pain, swelling, and restricted range of movement can cause significant discomfort, the symptoms resolve spontaneously within a few days to weeks and the response to nonsteroidal anti-inflammatory drugs (NSAIDs) is well documented. There is no longterm deformity or chronic damage to the joints or ligaments.9
Renal involvement is seen in 20% to 50% of the patients diagnosed with pediatric HSP.5,10 The earliest finding is microscopic hematuria with or without proteinuria.5 Children aged older than 4 years, purpura persisting for longer than 1 month, and severe GI bleeding are higher risk factors for developing renal disease. The renal symptoms take longer to manifest in comparison with the joint and abdominal symptoms. Several studies have shown that renal involvement was apparent within 3 months of appearance of the purpura in 97% of the patients and within 4 weeks for 75% of the patients.5,10 Based on this, weekly urinalysis and blood pressure measurements must be performed in the first 3 months after diagnosis. About 12% of the children with HSP end up with chronic renal failure about 3 to 4 years after diagnosis.5
Other clinical features that have been reported but are less common are headaches, intracranial hemorrhage, pulmonary hemorrhage, scrotal hematoma, and orchitis.
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