Background: Usually misdiagnosed and ignored in the literature, exercise-induced vasculitis (EIV) is not uncommon, occurring mostly in long-distance runners and in females after long walks, especially in hot weather.
Observations: I report 23 otherwise healthy patients (22 females, 1 male) who developed EIV after walking or hiking in hot weather. Erythematous, urticarial or purpuric plaques arose on the lower legs, not involving skin compressed by socks. Symptoms included itch, pain, and burning sensation. Lesions resolved after some days. Relapses were frequent at further muscular exercise, and could be prevented in some cases by compression hosiery, manual lymphatic drainage, intake of oedema protective agents, or steroids (local or systemic).
Investigations: Histopathology demonstrated leucocytoclastic vasculitis in five biopsies, and urticarial vasculitis in one. Extensive blood investigations have been performed in six patients and were negative. No clear relation with chronic venous disease (duplex or Doppler) had been established in 12 patients.
Conclusions: I suggest denominating this condition exercise-induced vasculitis. This clinical entity is well defined, but poorly recognized. The presentation of 23 original cases demonstrates its reality.