Vitiligo, in which there is patchy and often symmetrical depigmentation of the skin, surrounded by areas of increased pigmentation (Fig. 9.5), occurs in ten to twenty per cent of cases of Addison's disease. Its presence is almost invariably an indication that the cause of the adrenal failure is auto- immune adrenalitis. One of the patients described by Addison in his 1855 monograph had extensive vitiligo; however, this was the only case in which permission for post-mortem examination was refused.
