Minocycline Pigmentation of Heart Valves

Minocycline, a derivative of tetracycline, is a broad spectrum antibiotic used in the treatment of gram-positive and gram-negative infections. Benitz et al. (1) were the first to report black discoloration of the thyroid gland in rats, dogs, and monkeys given minocycline. Since that time, there have been numerous reports in the literature describing minocycline related black pigmentation of the skin, thyroid gland, and other sites. We report an unusual case of minocycline induced pigmentation of the cardiac valves and coronary vessels. The pigment stained with Fontana-Masson and was reduced with bleaching. The exact nature of the pigment is unclear; however, various theories have been advocated. Ochronosis is another cause of black pigmentation of the heart valves; the clinical history should allow distinction between the two.