methimazole and Hemosiderosis

Two cases of hyperthyroidism with hyperpigmentation are presented. In both cases, hyperpigmentation was seen on the lower extremities, most strikingly on the shins, backs of the feet and the nail bed. Histology of the pigmented skin showed basal melanosis and heavy deposition of haemosiderin around dermal capillaries and sweat glands. Treatment with mercazol in both cases resulted in no significant waning of pigmentation. Distribution of hyperpigmentation, haemosiderin deposition and poor response to the treatment may be characteristic features of the pigmentation caused by hyperthyroidism, and may represent differences from the pigmentation seen in Addison's disease.

Topics: Addison Disease; Adult; Antithyroid Agents; Hemosiderosis; Humans; Hyperpigmentation; Hyperthyroidism; Male; Melanosis; Methimazole; Middle Aged; Sweat Gland Diseases