Experimental hemosiderosis: relationship between skin pigmentation and hemosiderin.

Iron (totalling 7.5 mg per mouse in three doses) was injected into hairless mice to determine the relationship between skin pigmentation and hemosiderin deposition. The skin color reached its maximum 24 to 48 hours after the last injection and then gradually faded over the subsequent 8 months. In the skin, hemosiderin granules were present extracellularly between collagen bundles as well as within dermal macrophages, Langerhans cells and indeterminate dendritic cells of the epidermis. A larger amount of iron was deposited in the facial than in the dorsal skin, resulting in darker pigmentation of the former. This study suggests that brownish discoloration of skin in hemochromatosis might be attributable in some degree to accumulation of hemosiderin and that pronounced hyperpigmentation of the face in hemochromatosis might be due to increased activation of melanocytes by a high content of hemosiderin.