Which lesion is most characteristic of psoriasis?

• A. Hypopigmented macules on hands and forearms
• B. Pruritic pustules on finger webs and wrists
• C. Crusting vesicles around the mouth and face
• D. Scaling plaques on knees and elbows

Answer: (D)

Recognize psoriasis by its classic skin lesions: well‑defined, red plaques with silvery scales that most often appear on the extensor surfaces of the body, especially the knees and elbows. This pattern reflects rapid skin turnover with thickened epidermis and parakeratosis, producing the characteristic flaky, adherent scale. The distribution on knees and elbows is particularly typical, and lesions may be symmetrical and involve other areas such as the scalp or nails. The other descriptions point to different conditions—hypopigmented patches suggest vitiligo or tinea versicolor, itchy pustules on finger webs and wrists fit scabies or dyshidrotic dermatitis, and crusting vesicles around the mouth and face align with impetigo or herpes simplex—so the scaling plaques on extensor surfaces best match psoriasis.