Case Reports

8-year-old boy • palpable purpura on the legs with arthralgia • absence of coagulopathy • upper respiratory infection • Dx?

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THE CASE

An 8-year-old boy presented to his family physician (FP) with pharyngitis, nasal drainage, and a dry cough of 3 days’ duration. He denied any fever, chills, vomiting, or diarrhea. He had no sick contacts or prior history of streptococcal pharyngitis, but a rapid strep test was positive. No throat culture was performed at this time. The patient was started on amoxicillin 250 mg 3 times daily for 10 days.

On Day 7 of symptoms, the patient presented to the emergency department with elbow and knee pain, as well as mild swelling and purpura of his legs of 3 days’ duration. He was normotensive and reported no abdominal pain. A laboratory workup, including a complete blood cell count and differential, prothrombin time, partial thromboplastin time, comprehensive metabolic panel, creatinine kinase test, urinalysis, and chest radiograph, was normal, but his erythrocyte sedimentation rate (ESR) was mildly elevated at 22 mm/h (reference range, 0–20 mm/h). The patient was discharged on acetaminophen 15 mg/kg every 4 hours as needed for pain.

THE DIAGNOSIS

Based on the distinctive palpable purpura on the legs, arthralgia, upper respiratory infection, and lack of thrombocytopenia and coagulopathy, a presumptive diagnosis of Henoch-Schönlein purpura (HSP) was made.

On Day 9 of symptoms, the patient returned to his FP’s office because the arthralgia persisted in his ankles, knees, and hips. He had developed lower back pain, but the pharyngitis and upper respiratory symptoms had resolved. On physical examination, he was normotensive with a normal abdominal exam. The patient reported that it hurt to move his wrists, hands, elbows, shoulders, knees, and ankles. He also had mild swelling in his left wrist, hand, and ankle. The paraspinal muscles in the lower thoracic and lumbar back were mildly tender to palpation. A complete metabolic panel and urinalysis were normal. Dermatologic examination revealed discrete purpuric lesions ranging from 1 to 8 mm in diameter on the child’s shins, thighs, and buttocks. Urinalysis, blood urea nitrogen, and creatinine kinase were normal. His ESR remained mildly elevated at 24 mm/h. Since there was no evidence of glomerulonephritis, ibuprofen 10 mg/kg every 8 hours as needed was added for pain management.

The child was brought back to his FP on Day 18 for a scheduled follow-up visit. The parents reported that his arthralgia was improved during the day, but by the evening, his knees and ankles hurt so much that they had to carry him to the bathroom. On physical examination, he still had palpable purpura of the legs. There was no swelling, but his joints were still tender to palpation. His parents were reminded to give him ibuprofen after school to control evening pain. Over the next 2 weeks, the patient showed gradual improvement, and by Day 33 the rash and all of the associated symptoms had resolved.

DISCUSSION

Clinical presentation. HSP is an IgA immune complex vasculitis in which abnormal glycosylation of IgA creates large immune complexes that are deposited in the walls of the skin capillaries and arterioles. The primary clinical finding in HSP is a distinctive nonthrombocytopenic purpuric rash that is not associated with coagulopathy and is characterized by reddish purple macules that progress to palpable purpura with petechiae (Figure). Lesions generally are distributed on the legs or buttocks but also may appear on the torso or arms. Flu-like symptoms, such as fever, runny nose, and cough, are common.

Nonthrombocytopenic purpuric rash of Henoch-SchÖnlein purpura

A preceding upper respiratory infection has been found in 37% of patients,1 and in patients with renal complications, 20% to 50% have been found to have a group A Streptococcus infection.2 Other associations include food allergies, cold exposure, insect bites, and drug allergies.

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