A 50-year-old man with end-stage renal disease presented with an intensely pruritic rash on his upper and lower extremities, abdomen, and back. The rash had appeared spontaneously three months before the visit and was not associated with systemic symptoms. The patient had a history of type 2 diabetes mellitus and was receiving dialysis.

Physical examination revealed numerous papules of various sizes (Figure 1). Each lesion had a central depression and an erythematous halo. The rash featured hyperkeratosis but no fluctuance or induration. A punch biopsy of a lesion on the upper right quadrant of the abdomen was performed. It revealed a keratin-filled channel in the shape of a funnel with histocyte-rich infiltrate and fibrosis at the base of the invagination. Grocott-Gomori methenamine–silver nitrate and periodic acid–Schiff stains were negative for fungal elements.

QUESTION

Based on the patient's history and physical examination, which one of the following is the most likely diagnosis?

• A. Acquired perforating dermatosis.

• B. Dermatofibroma.

• C. Keratosis follicularis.

• D. Molluscum contagiosum.

• E. Prurigo nodularis.