The occasional patient whose illness is associated with generalized hyperpigmentation presents the physician with a challenging diagnostic problem. The increased deposition of melanin is characteristically diffuse and deepens the coloration of the palmar creases, intertriginous areas, oral mucous membranes, and recent scars. Often it accentuates pressure points such as the knuckles, elbows, and knees. The wide variety of disease processes that may cause such hyperpigmentation demands a working knowledge of pathogenesis and differential diagnosis (Table).
Although not frequently cited, the observation that hyperpigmentation occurs in pernicious anemia (Ogbuawa et al, this issue of the Archives [p 388]), is not new. Herbert1 has emphasized the occasional occurrence of hyperpigmentation in patients with a vitamin B12 or folic acid deficiency. Vitamin B12 deficiency with hyperpigmentation has been noted in whites, East Indians, Orientals, and in the black race.2 If pernicious anemia in blacks is as rare as has