Pustular eruption on the forearm from a case of pemphigus, occurring on the flexor surface of the left forearm. It began by the appearance of a few small bullae, which quickly became pustular. Many of these burst and formed crusts. The surrounding skin appears red and inflamed. From a man aged 34, who had occasionally had similar attacks of pemphigus in the past ten years. Leonard Mark, 1893. Pemphigus is a rare group of blistering autoimmune diseases that affect the skin and mucous membranes.