CASE #1: Leukocytoclastic vasculitis
The woman had idiopathic leukocytoclastic vasculitis (LCV), a clinicopathologic entity affecting the small vessels of the skin. It is also known as “hypersensitivity vasculitis,” “allergic vasculitis,” and “allergic angiitis.” This condition represents a type III, or immune complex-mediated, hypersensitivity reaction, in which immune complex lodges in capillaries. Neutrophils burst in response, leading to a vasculitis and extravasation of blood. It is typically characterized by round, 1- to 5-mm palpable or inflammatory purpura on the lower legs. The lesions coalesce to form plaques and may ulcerate.
LCV is often an acute self-limited condition, but chronic forms can occur. Involvement is typically limited to the skin, although cases have been seen in the kidneys, GI tract, and other organs. Morbidity and mortality are minimal if the condition involves only the skin. Some patients have no associated symptoms, while others complain of itching, burning, or pain.
Up to half of all cases are of unknown etiology. The most common causes of LCV are medication reactions (e.g., to beta-lactams), streptococcal infections, and hepatitis. Uncommon causes include collagen vascular disease, inflammatory bowel disease, Waldenström's macroglobulinemia, cryoglobulins, and HIV.
LCV can be confused with a number of conditions, including Henoch-Schönlein purpura, scurvy, purpuric drug reactions, benign pigmented purpura, other forms of vasculitis, and macular Kaposi's sarcoma. A complete history, including recent respiratory infections, IV drug use, hepatitis, transfusion, and travel, as well as symptoms or history of inflammatory bowel disease and collagen vascular diseases, is required in suspected cases. A review of symptoms should assess fever, arthralgia, arthritis, myalgia, abdominal pain, diarrhea, hematochezia, cough, hemoptysis, sinusitis, paresthesia, weakness, and hematuria.
Biopsy will reveal vascular and perivascular infiltration of polymorphonuclear leukocytes with nuclear dust. A hallmark of LCV is the presence of fibrinoid necrosis, a ring of fibrin obliterating the vessel walls.
Laboratory tests help determine the presence of systemic disease as well as identify any associated disorders. Requisite tests include complete blood count, erythrocyte sedimentation rate, blood chemistry, and urinalysis. If bowel symptoms are present, a stool guaiac test should be performed. Patients without an obvious cause of LCV should have ANA, antineutrophil cytoplasmic antibody, and rheumatoid factor determinations. Complement levels may be ordered for patients who have lupus erythematosus or urticarial vasculitis. Streptozyme or antistreptolysin-O titers, serum protein electrophoresis, cryoglobulins, and hepatitis C antibody are also helpful. Finally, HIV testing should be performed in patients who are at high risk of the virus.
A skin biopsy for direct immunofluorescence distinguishes LCV from forms of immunoglobulin A vasculitis, such as Henoch-Schönlein purpura. A chest x-ray is a helpful part of an LCV evaluation.
Isolated, idiopathic LCV usually resolves without treatment. If related to other conditions, treatment of these conditions can help the LCV to resolve. Prednisone (1-2 mg/kg), colchicine, or dapsone may be administered for patients with or without joint manifestations. Our patient decided to forgo therapy. Several months after presentation, her rash resolved without complication.