7-Year-Old With a Painful Rash.

Abstract

An African American boy aged 7 years presented with right ankle pain, overlying soft tissue erythema, and swelling. He was diagnosed with cellulitis and prescribed 10 days of sulfamethoxazole and trimethoprim.Althoughhis right ankle pain and swelling initially improved, he presented 1 week later with left ankle and right knee pain and swelling. He had a tender, nonerythematous, subcutaneous 1-cm nodule above the right olecranon. Laboratory results were notable for an elevated erythrocyte sedimentation rate of 44mm/h, a C-reactiveprotein level of0.84mg/L (to convert tonanomolesper liter,multiplyby9.524), an antistreptolysinO titer of 1150 IU/mL, andananti-DNaseB titer of961U/mL. The results of the rapid strep test and throat culturewere normal, but given his constellation of symptoms, he was diagnosed with acute rheumatic fever. Echocardiogram and electrocardiogram were normal, and he was treated with amoxicillin. Four days after discharge, he developed new painful skin lesions on his elbows, forearms, and legs. He remained afebrile but continued to complain of persistent left ankle and right knee pain. On examination, he had amultitude of skin lesions, including a raised follicular rash on both shins; painful flesh-colored raised nodules on the right knee, left index finger, and elbows; and painful raised circular violaceous papulonecrotic lesions with surrounding erythema and induration on the bilateral shins, left knee, right upper arm (Figure, A), and bilateral buttocks. Admission laboratory results included a hemoglobin concentration of 9.3g/dL (toconvert togramsper liter,multiplyby 10), indicatingnormocytic anemia; awhite blood cell count of 11 500/μL (to convert to × 109/L,multiply by0.001), with 64%neutrophils; anelevatederythrocyte sedimentation rateof46mm/h;andaC-reactiveprotein level of0.57mg/L. Punchbiopsywasobtained froma lesion (Figure, B),which showedadermal neutrophilic infiltrate with normal Gram and Grocott methenamine silver stains. A Papulonecrotic lesion B Punch biopsy