Derm Dx: Striking pigmentation on a former chemical plant worker

A 43-year-old man who has impaired mentation and currently resides in an extended-care facility is being followed for discoid lupus erythematosus affecting his right cheek. On examination, in addition to facial plaque, striking generalized pigmentation is noted, most prominently on his face and arms. According to caretakers, the pigmentation has been present for decades and is related to past occupational ...