Vasculitis is an uncommon disorder characterized by an aberrant immune response that results in blood vessel damage. It is considered to be a reaction pattern with numerous potential triggers. Possible inciting causes include medications, vaccinations, infectious disease, parasites, adverse reactions to food, familial disease, metabolic derangements, neoplasia, and idiopathic forms. Cutaneous lesions are usually well-demarcated and consist of edema, purpura, alopecia, erosions, focal punctate ulcers, crusting, necrosis, and/or eschar formation (Figure 5). Although lesions may occur anywhere, the extremities, tips of the ears, oral mucosa, and tail are more commonly affected.7 Patients may also display systemic signs, which should correlate with disease severity.
Diagnosis is based on clinical suspicion and compatible skin biopsy results. Newer lesions show the best diagnostic yield of biopsy specimens, as chronic lesions may only reveal ischemic changes.7 Following a confirmed diagnosis, the patient should be evaluated for specific etiologies via blood work, urinalysis, tick-borne disease testing, imaging studies, coagulation profiles, and immunologic assays. In cases in which diagnostic testing fails to identify a probable cause, a diet elimination trial should be considered, as a retrospective study previously identified food allergy as the underlying etiology in a subset of cutaneous vasculitis cases.8
Therapy should focus on removal or treatment of the underlying cause and immunomodulation. Prognosis is highly variable and dependent on the underlying cause, lesion extent, and degree of systemic involvement.