Reflex sympathetic dystrophy is a unique traumatic disorder with unusual cutaneous signs. The case of a patient with an uncommon, poorly understood, sharply marginated geometric zone of erythema is reported. Pseudo-Kaposi's sarcoma developed in the same patient in the foot affected by reflex sympatbetic dystrophy, an association not previously reported. For effective treatment this disorder must be diagnosed as early as possible. The clinical stages of evolution through which reflex sympathetic dystrophy progresses are described.