Pigmented coalescing papules on the dorsa of the hands: pigmented colloid milium associated with exogenous ochronosis

Colloid milium is a rare cutaneous deposition disorder that frequently occurs in areas of chronic sun exposure such as the face, neck and backs of the hands and is characterized by multiple small, discrete, usually amber-colored, dome-shaped papules that cluster to form large plaques. A 50-year-old white woman with esophageal squamous cell carcinoma was referred to us with asymptomatic, slowly spreading lesions localized to the dorsa of her hands which had been present for 4 years. The condition was diagnosed histopathologically as pigmented colloid milium associated with exogenous ochronosis (EO). Colloid milium associated with EO is very rarely reported in the published work. We think that a possible interaction between sunlight and exposure to chemical fertilizers may have played a role in the pathogenesis of both of the disorders in our case.