A 21-year-old woman presented with a 3-day history of a painful purpuric rash on her lower extremities (Figures 187-1 and 187-2). The lesions had appeared suddenly, and the patient had experienced no prior similar episodes. The patient had been diagnosed with a case of pharyngitis earlier that week and was given a course of clindamycin. She had not experienced any nausea or vomiting, fever, abdominal cramping, or gross hematuria. Urine dipstick revealed blood in her urine, but no protein. The typical palpable purpura on the legs is consistent with Henoch-Schönlein purpura (HSP), also known as IgA vasculitis.
Henoch-Schönlein purpura presenting as palpable purpura on the lower extremity. The visible sock lines are from lesions that formed where the socks exerted pressure on the legs. (Reproduced with permission from Richard P. Usatine, MD.)
Close-up of palpable purpura from the patient in Figure 187-1. Some lesions look like target lesions, but this is Henoch-Schönlein purpura and not erythema multiforme. (Reproduced with permission from Richard P. Usatine, MD.)
Vasculitis refers to a group of disorders characterized by inflammation and damage in blood vessel walls. They may be limited to skin or may be a multisystem disorder. Cutaneous vasculitic diseases are classified according to the size (small vs. medium to large vessel) and type of blood vessel involved (venule, arteriole, artery, or vein). Small- and medium-size vessels are found in the dermis and deep reticular dermis, respectively. While the classifications have not changed, the nomenclature has in an effort to characterize lesions based on the pathologic findings and underlying disease process. The most notable changes during the Chapel Hill Consensus Conference of 2012 changed HSP to IgA vasculitis (IgAV), Wegener's granulomatosis to granulomatosis with polyangitis (GPA), and Churg-Strauss to eosinophilic granulomatosis with polyangitis (EGPA).1 The clinical presentation varies with the intensity of the inflammation and the size and type of blood vessel involved.2
Hypersensitivity vasculitis is also known as leukocytoclastic vasculitis.
HSP (IgAV) is a type of leukocytoclastic vasculitis.
HSP (IgAV) (Figures 187-1, 187-2, 187-3) occurs mainly in children with an incidence of approximately 1 in 5000 children annually.3 It results from immunoglobulin (Ig) A–containing immune complexes in blood vessel walls in the skin, kidney, and GI tract. HSP (IgAV) is usually benign and self-limiting and tends to occur in the springtime. A streptococcal or viral upper respiratory infection often precedes the disease by 1 to 3 weeks. Prodromal symptoms include anorexia and fever. Most children with HSP (IgAV) also have joint pain and swelling with the knees and ankles ...