Which dermatosis presents with erythematous plaques with silvery scales, well-marginated, often with nail pitting?

• A. Seborrheic dermatitis
• B. Eczema
• C. Psoriasis
• D. Lichen planus

Answer: (C)

Plaque psoriasis is suggested by well-demarcated, erythematous plaques with a silvery, adherent scale, and nail involvement often shows pits from the nail matrix. This combination—sharp-edged red plaques with silvery scales and pitted nails—is classic for psoriasis. Seborrheic dermatitis tends to have greasy yellow scales and less clearly defined borders, often on the scalp and face, and nail pitting is not typical. Eczema features itchy, inflamed skin with possible weeping and thickened areas but the scales are not characteristically silvery nor are margins as well defined. Lichen planus presents as purple, flat-topped pruritic papules with possible mucosal involvement; nail pitting is not a defining feature.