Henoch-Schönlein purpura is a systemic leukocytoclastic vasculitis involving small vessels. The small vessel vasculitis is associated with IgA antigen-antibody complex deposition in areas throughout the body. Palpable purpura typically is seen on the skin, which characteristically involves dependent areas such as the legs and the buttocks. Lesions normally are present bilaterally in a symmetric distribution. Initially, the lesions develop as erythematous macules that progress to purple, nonblanching, palpable, and purpuric plaques.1 Henoch-Schönlein purpura most commonly involves the skin; however, other locations for the immune complexes include the gastrointestinal tract, joints, and kidneys.2 The cause for the body's immunogenic deposition response is unknown in a majority of cases.
Henoch-Schönlein purpura most commonly is seen in the pediatric population with a predilection for males.3 The incidence in the pediatric population is 13.5 to 20 per 100,000 children per year; HSP is more rare in adults.4-6 Henoch-Schönlein purpura most often is a self-limiting disease that requires only supportive treatment. The signs and symptoms last 4 to 6 weeks in most patients and resolve completely in 94% of children and 89% of adults.7 Renal involvement carries a worse prognosis. Adult patients have a higher incidence of renal involvement, renal insufficiency, and subsequent progression to end-stage renal disease.3,8-10 In a study by Hung et al8 of 65 children and 22 adult HSP patients, 12 adults presented with renal involvement in which hematuria or proteinuria were present. Of them, 6 progressed to renal insufficiency (defined as having a plasma creatinine concentration>1.2 mg/dL).8 Fogazzi et al11 reported similar findings; 8 of 16 patients affected with HSP progressed to renal insufficiency with creatinine clearances ranging from 31 to 60 mL/min, and 3 patients required chronic dialysis. Pillebout et al9 evaluated 250 adults with HSP and 32% reached renal insufficiency with creatinine clearances of less than 50 mL/min, with 11% of patients developing end-stage renal disease. The degree of hematuria and/or proteinuria has been shown to be an effective prognostic indicator.9,10 Coppo et al10 found a similar prognosis among children and adults with HSP-related nephritis.
Our patient described the burning sensation as occurring bilaterally from the knees down to the feet, which provided an additional clue that small vessel vasculitis was involved, as occluded blood vessels can cause ischemia to nerves and perivascular involvement can affect nearby neural structures. Sais et al12 demonstrated that paresthesia in the setting of HSP was a risk factor for systemic involvement. Of note, our patient's paresthesia lasted only several days.
The cause of HSP is not always as evident in the adult population as in the pediatric population. Early diagnosis of HSP in adults may allow for the proper instatement of treatment to deter long-term renal complications. Follow-up with urinalysis is recommended because a small percentage of patients have a late progression to renal failure.13,14
Because the dermatologists involved in this case knew where and what types of biopsies to perform, a correct diagnosis was obtained quickly, allowing for the correct therapeutic intervention. After the diagnosis of HSP is made in an adult, nephrology should be consulted early in the treatment course.