Lumbar swelling and migrating edema in 3- and 4-year-old boys

Henoch-Schönlein purpura is the most common systemic vasculitis in children, characterized by IgA deposits in small vessels. The etiology is unknown, but Henoch-Schönlein purpura typically follows an upper respiratory infection, or less frequently other infective or chemical triggers. The classic tetrad of symptoms includes palpable purpura (mandatory criterion), arthralgias, abdominal pain, and renal involvement. However, the cutaneous rash of Henoch-Schönlein purpura is not the presenting sign in approximately one-quarter of patients. Moreover, the other typical manifestations can present isolated or nuanced; for that reason, a prompt diagnosis may be challenging. Other clinical findings such as subcutaneous edema in hands, ankles, and feet, are quite common at pediatric Henoch-Schönlein purpura onset. Edema occurring in other locations (i.e facial and genital swelling), is uncommon, but can be a helpful additional clinical sign of Henoch-Schönlein purpura. To our knowledge, only two cases of lumbar swelling as Henoch-Schönlein purpura presentation signs have been described in literature so far.