DP21 Exercise-induced capillaritis: an uncommon presentation with characteristic histopathology

Abstract

Exercise-induced capillaritis is an under-recognized variant of pigmented purpuric dermatoses, characterized by transient petechial or purpuric eruptions precipitated by physical exertion. We report the case of reproducible, exercise-associated capillaritis, with histopathological findings supporting the diagnosis and highlighting the role of biopsy in distinguishing this benign condition from other vasculopathic dermatoses. A 65-year-old woman with no significant past medical history presented with a several-­year history of a recurrent, asymptomatic rash affecting the lower extremities. The eruption persistently recurred after prolonged walking and resolved over a period of days to weeks without residual pigmentation. She denied systemic symptoms, new medications, infections, or personal or family history of autoimmune or vasculitic disease. Physical examination performed shortly after an exercise-induced episode revealed scattered, nonblanching erythematous-to-violaceous macules and petechiae on the bilateral lower legs, without oedema, ulceration or livedoid change. Given concern for possible small-vessel vasculitis or pigmented purpuric dermatosis, a punch biopsy was obtained from an active lesion. Histopathological examination showed an inflammatory infiltrate in the superficial dermis, comprised of an admixture of eosinophils and lymphocytes, with occasional neutrophils and nuclear dust, in a predominantly perivascular distribution. There was swelling of the endothelial cells with evidence of fibrin deposition. The overlying epidermis was unremarkable. This was consistent with findings in other reported cases of exercise-induced vasculitis. Exercise-induced capillaritis, also referred to as golfer’s purpura, is thought to result from increased hydrostatic pressure and capillary fragility during prolonged ambulation, particularly in warm conditions. It may mimic vasculitis, thrombocytopenic purpura or early pigmented purpuric dermatoses, often prompting biopsy. Recognition of its characteristic clinicopathological features is essential to avoid unnecessary laboratory evaluation and treatment. This case underscores the importance of clinicopathological correlation in transient purpuric eruptions. Awareness of exercise-induced capillaritis among dermatopathologists can facilitate accurate diagnosis and prevent misclassification as vasculitis or systemic disease.