This is a rare condition seen in very particular circumstances.

The patient will have diabetes and renal failure, probably requiring dialysis. The lesions will be on the legs and will be keratotic papules, often purplish in colour like these and they are usually itchy. This condition is known as reactive perforating collagenosis. In this condition altered collagen is extruded through a cup shaped invagination of the epidermis giving the papule with a keratotic core. They are sometimes mistaken for hypertrophic lichen planus on the lower legs. Phototherapy with UVB light can be therapeutic as can oral retinoids but complete resolution is rare without a renal transplant.

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