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Case Reports

Abstract

Erythematous, urticarial, or purpuric macules on the lower legs can occur after extensive walking during hot weather. A 48-year-old female mail carrier presented with recurrent pink edematous to urticarial papules coalescing into plaques over the lower legs. She reported flares every summer following her 10-mile mail route. Acute flares were associated with itching or burning and resolved with avoidance of strenuous activity in hot temperatures. Screening labs including ANA, dsDNA antibody, rheumatoid factor, were negative. Punch biopsy showed perivascular and interstitial mixed infiltrate with eosinophils, scattered neutrophilic debris and red blood cell extravasation. Although fibrin was not appreciated, the findings resembled urticarial vasculitis. Given the clinical history and pathology findings, a diagnosis of exercise-induced vasculitis (EIV) was made. EIV classically occurs on the lower legs of healthy active people after physical exertion in a hot climate. The morphology varies from erythematous, urticarial to purpuric, but it is not associated with systemic findings. While usually asymptomatic, it can be associated with pruritus, pain, or burning. Resolution occurs within ten days, in the absence of further exertion. Limited reports of the histopathology usually describe leukocytoclastic vasculitis, but it can lack fibrin or vascular necrosis suggesting that this may not be a true primary vasculitis and the histopathology may vary based on timing of the biopsy. This case highlights an under-recognized entity that may be misdiagnosed as systemic vasculitis.