Subacute loss of vision in one eye · rash on hands and feet · plaques with scaling on genitals · Dx?

A 67-year-old man presented to the hospital with subacute loss of vision in his left eye. The visual changes began 2 weeks earlier, with a central area of visual loss that had since progressed to near complete vision loss in the left eye. Physical examination revealed patchy alopecia, a scaling and hyperkeratotic rash of his hands and feet, and blanching, erythematous plaques with associated scaling on the scrotum and glans penis. Ophthalmologic examination revealed 1/200 vision in his left eye with a large plaque occupying a substantial portion of the superior quadrant, smaller perifoveal plaques in both of his eyes, and a small infiltrate above the left optic nerve head. The patient also described fatigue, loss of taste, and an unintentional weight loss of 7 to 10 kg over the previous 6 months. He had seen his primary care provider 3 months prior for a burning sensation and scaling rash on his feet and hands, and was prescribed a topical steroid.