Comment
Incidence and Clinical Characteristics
Acute hemorrhagic edema of infancy is an uncommon leukocytoclastic vasculitis first described in the United States by Snow1 in 1913. Other names for the disorder include acute hemorrhagic edema of young children, cockade purpura and edema, Finkelstein disease, and Seidlmayer disease.2 Boys are affected more often than girls, with most children presenting at 6 to 24 months of age. Most affected children experience a prodrome of simple respiratory tract illness (most common), diarrhea (as in our case), or urinary tract infection.2 The exact pathophysiology behind AHEI is unknown, but it is thought to be an immune complex–mediated disease evidenced by the fact that infection, use of medication, or immunization precedes most cases.3,4
Diagnosis
Acute hemorrhagic edema of infancy is diagnosed clinically, with or without the support of skin biopsy. It should be differentiated from HSP because of renal and GI sequelae that HSP portends compared to the benign course of AHEI.2 Notably, some health care providers consider AHEI a benign variant of HSP.2,3
Characteristically, AHEI patients are nontoxic-appearing infants with a low-grade fever who develop relatively large (1–5 cm) targetoid purpuric lesions and indurated nonpitting edema of the extremities.2,5 Purpura in AHEI frequently occurs on the face, ears, and upper and lower extremities, whereas purpura in HSP most commonly presents on the buttocks and extensor legs with sparing of the face. Henoch-Schönlein purpura most often affects children aged 3 to 6 years compared to AHEI’s younger demographic (age <2 years).4,5 Clinically, HSP presents with palpable purpura and 1 or more of the following features: diffuse abdominal pain, arthritis/arthralgia, renal involvement, and skin or renal biopsy showing predominant IgA deposition.2,6
Both AHEI and HSP show leukocytoclastic vasculitis on histopathology.2-4,6,7 Positive perivascular IgA staining on DIF is strongly associated with HSP, but nearly one-quarter of AHEI cases also show this deposition pattern2,4,7; therefore, DIF alone cannot exclude a diagnosis of AHEI.
Differential Diagnosis
Alternative diagnoses to consider with AHEI include drug-induced vasculitis, erythema multiforme, HSP, Kawasaki disease, meningococcemia, nonaccidental skin bruising, Rocky Mountain spotted fever, septic vasculitis, and urticarial vasculitis (Table).2-4,6-8
Treatment
Acute hemorrhagic edema of infancy is self-limited, with only rare reports of extracutaneous involvement. Supportive treatment is indicated because spontaneous recovery without sequelae is expected within 21 days.2,3,6 If edema is symptomatic, as was the case with our patient, corticosteroids may shorten the disease course.3
Conclusion
Our case highlights the need to combine clinical history, physical examination, and histopathologic analysis to differentiate between AHEI and HSP, which is important for 2 reasons: (1) it helps with the decision to undertake active or observational treatment, and (2) it helps the clinician counsel the patient and guardians regarding potential associated renal and GI risks.