Clinical Pearls & Morning Reports
Large-vessel vasculitis typically affects the aorta and its branches and does not cause purpuric skin lesions. Because medium-sized arteries supply a larger area of the skin than do small arteries, medium-vessel vasculitis leads to skin ulcers, nodules, and livedo racemosa, whereas small-vessel vasculitis typically causes petechiae and purpura. Read the latest Case Record of the Massachusetts General Hospital.
Q. What are some of the causes of purpura?
A. Purpuric lesions are generally caused by extravasation of blood from damaged blood vessels. Nonpalpable purpura may be due to thrombocytopenia, systemic illness (e.g., amyloidosis), infection, a hypercoagulable state, nutritional deficiency (e.g., scurvy), sun exposure (e.g., solar purpura), and idiopathic cutaneous conditions (e.g., Schamberg’s disease). Palpable purpura that involves dependent areas of the body is strongly suggestive of a small-vessel vasculitis.
Q. How are the small-vessel vasculitides classified?
A. Small-vessel vasculitides can be divided into two categories: antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis and immune complex–mediated vasculitis. The three types of ANCA-associated vasculitis are eosinophilic granulomatosis with polyangiitis, microscopic polyangiitis, and granulomatosis with polyangiitis. Other than vasculitis associated with drug reactions, the most common types of immune complex–mediated vasculitis are cryoglobulinemic vasculitis and IgA vasculitis (formerly Henoch–Schönlein purpura).
A: IgA vasculitis is unique among vasculitides because it is frequently triggered by infection or medication use and is often self-limited. A broad range of infections, including streptococcal and nonstreptococcal infections, have been implicated in the development of IgA vasculitis. IgA vasculitis occurs most commonly in children, and the majority of cases prove to be self-limited illnesses that require no specific therapy. The four organ systems that are most commonly affected by the disease are the skin, the joints, the bowel, and the kidneys. In contrast to other vasculitides, IgA vasculitis is associated with the onset of cutaneous lesions before or shortly after the onset of extracutaneous manifestations in most cases. Gastrointestinal and renal involvement are commonly seen in patients with IgA vasculitis. However, approximately one third of patients with IgA vasculitis do not have renal or gastrointestinal involvement. Although articular manifestations of IgA vasculitis can involve any joint, they tend to involve the large joints of the legs. Gastrointestinal involvement in IgA vasculitis is usually characterized by colicky abdominal pain that often occurs before the eruption of palpable purpura on the skin and sometimes leads to exploratory surgery for a presumed acute abdomen.
A: Leukocytoclastic vasculitis represents a vascular reaction pattern in the skin and is not a specific diagnosis. It can be a manifestation of IgA or urticarial vasculitis or may be idiopathic. It may also result from underlying infections, medication use, inflammatory disorders, and cancer. The pathogenesis involves deposition of circulating immune complex in the walls of small vessels and activation of the complement system. The subsequent influx of neutrophils leads to the release of lysosomal enzymes, which damage the vessel wall, leading to fibrin deposition and extravasation of erythrocytes. In order to help narrow the differential diagnosis for leukocytoclastic vasculitis, direct immunofluorescence staining can be performed. It is important to note that IgA-associated leukocytoclastic vasculitis is not pathognomonic for IgA vasculitis, since IgA deposition may also be seen in leukocytoclastic vasculitis that is due to cryoglobulinemia or the use of certain medications, including tumor necrosis factor (TNF)-α inhibitors.