Cutaneous small vessel vasculitis (CSVV) typically presents with a combination of palpable purpura, erythematous papules, hemorrhagic vesicles, or urticarial plaques (Fig. A, B).1 Lesions tend to occur seven to 10 days after an inciting event and favor dependent or traumatized areas. Cutaneous lesions are generally asymptomatic, although they can be associated with burning, pain, or pruritus.2,3 Systemic symptoms can include fevers, weight loss, arthralgias, myalgias, and gastrointestinal, genitourinary or neurologic symptoms. Presence of these symptoms should raise the suspicion of a systemic vasculitis. Epidemiologic studies have shown that both sexes and all ages can be affected, however, vasculitis is generally more common in adults.4 Other names for CSVV include: cutaneous necrotizing venulitis, cutaneous leukocytoclastic angiitis, cutaneous leukocytoclastic vasculitis, and hypersensitivity angiitis.

Evaluation
CSVV primarily affects postcapillary venules of the skin,5 thus one of the first steps in the evaluation is to confirm the diagnosis by biopsy. Histologic evaluation of these lesions will demonstrate thickened or smudgy vessels also known as fibrinoid degeneration as a result of fibrin deposition and marked edema (Fig. C, D). Surrounding this is a predominantly neutrophilic infiltrate, although mononuclear cells and eosinophils can be found. The karyorrhectic nuclear debris or nuclear dust gives the infiltrate a dirty or smudgy appearance. Although these findings are helpful, biopsy results often are not available for several days, therefore management should initially proceed based upon the clinical evaluation.

Since CSVV can be seen in a heterogeneous group of disorders, it is primarily considered a cutaneous reaction pattern. The most common causes can be divided into several broad categories (with relative frequency) including: drug reactions (15 percent), infections (20 percent), inflammatory disorders (20 percent), malignancy (five percent) and idiopathic (40 percent). Therefore, the evaluation should start with a detailed drug history focusing on recent changes and including over the counter medications (Table 1).

The most commonly encountered medications include: antibiotics, sulfas, anti-tumor necrosis factor alpha (anti-TNF-a) agents, cyclo-oxigenase-2 (COX-2) inhibitors, granulocyte colony stimulation factor (G-CSF), hydralazine, leukotriene inhibitors, minocycline and nonsteroidal anti-inflammatory agents.6

The next broad category is infections, with the most common types being: Beta-hemolytic streptococci, Mycobacterium tuberculosis, Mycoplasma pneumonia, Hepatitis C, Hepatitis B, and human immunodeficiency virus (HIV).2,3 Therefore, the work-up should include anti-streptolysin O titers (ASO), purified protein derivative (PPD), Chest X-ray, hepatitis, and HIV screening.

The third broad category is inflammatory disorders, specifically lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease.7 Therefore, it is important to test for antinuclear antibodies (ANA), rheumatoid factor (RF), erythrocyte sedimentation factor (ESR) and fecal occult blood.

The final broad category is malignancy, with the most common disorders being myeloproliferative in origin.8 These include multiple myeloma, myelodysplasia, myeloproliferative disorders, lymphoproliferative disorders, and hairy cell leukemia. As such, peripheral smears, bone marrow biopsies, and immune blotting are often useful.

Before an evaluation is complete, it is also necessary to exclude systemic activity by evaluating the patient's complete blood count, complete metabolic panel, and urine analysis. When the clinical history is integrated with these tests, it is possible to find an etiology for the CSVV about half of the time. It is also critical to exclude other conditions that can mimic CSVV,2,3 such as cryoglobulinemia, Henoch-Schonlein purpura, and polyarteritis nodosa. Therefore, testing for cryoglobulins, biopsy for direct immunofluorescence (DIF) and anti-neutrophil cytoplasmic antibody (ANCA) are also useful.

Treatment
Initially, the decision to treat versus clinically observe depends upon the severity of the CSVV and the degree of systemic involvement. As the clinician completes the work-up and considers the results of any tests or studies, he or she should investigate the possible causation of the reaction and monitor for development of new lesions while deciding upon treatment. If a drug etiology is suspected it is critical to discontinue the medication as early as possible.3 When infectious, inflammatory, or malignant disorders are identified, an attempt should be made to treat them.

Although the prognosis depends upon a number of variables, it is important to note that the vast majority of lesions will resolve in a few weeks to months.1 Prior to initiation of medication for CSVV, it is important to note that most studies to date fall short of the gold standard: randomized control trial data. This is likely due to diverse etiologies for the vasculitis and the inability to obtain a uniform population of patients. Yet, encouraging data exist for medications that are classically used to treat neutrophilic dermatoses including colchicine9 and dapsone10 as well as limited data for oral corticosteroids.11 If systemic symptoms are present, it may be necessary to initiate systemic immunosuppression12 with azathioprine, cyclosporine, or methotrexate, depending upon the underlying etiology.