An 8-month-old boy with purpuric skin lesions. Acute hemorrhagic edema of infancy.

A previously healthy 8-month-old Hispanic boy presented with a 5-day history of an erythematous, non-pruritic papular eruption on both legs. The eruption was initially diagnosed as impetigo by his primary care practitioner but progressed despite trimethoprim / sulfamethoxazole therapy, with extension to the face, trunk, and all extremities. When the patient subsequently developed a fever of 100.8° F, emesis, diarrhea, and upper respiratory symptoms, he was referred to the pediatric dermatology clinic for evaluation. Further questioning revealed a 3-day febrile illness 6 weeks prior to presentation that was treated with ceftriaxone. Review of systems failed to identify any hematuria, blood in stool, or abdominal pain, but the parents did report swelling of the extremities and face, as well as decreased oral intake. On examination, the infant was in no apparent distress, afebrile, and had mild rhinorrhea. His mucous membranes were unaffected, and no lymphadenopathy or hepatosplenomegaly was noted. Cutaneous exam revealed numerous edematous erythematous to violaceous plaques on the cheeks, arms, buttocks, and legs with minimal involvement of the trunk. Several lesions on the arms had a distinct cockade (rosette or iris-like) pattern. There were no vesicles, bullae, or necrosis. Edema of the bilateral lower extremities was noted. Laboratory work up revealed a normal complete blood count (CBC), comprehensive metabolic panel, creatinine, and urinalysis. Platelets were borderline elevated at 439 TH/μL (140-440 TH/μL), and erythrocyte sedimentation rate and C-reactive protein (CRP) were minimally elevated at 22 mm (0-15 mm) and 3.1 mg/dL (0.0-0.99 mg/dL), respectively.