Which skin condition is characterized by erythematous papules and plaques?

The skin condition characterized by erythematous papules and plaques is psoriasis. This chronic inflammatory disease is known for its distinctive appearance, which often includes well-defined, red, raised lesions covered by silvery-white scales. The papules can coalesce to form plaques that typically present on extensor surfaces like elbows, knees, and sometimes on the scalp or lower back. The erythematous nature of these lesions is due to underlying inflammation, which is a hallmark of the condition.

While eczema, also known as atopic dermatitis, can present with erythematous areas, it typically has a more itchy, dry, and weepy appearance and often includes vesicles or crusting rather than the well-defined plaques seen in psoriasis. Contact dermatitis, which arises from exposure to irritants or allergens, can also cause erythema and papules but is usually associated with a specific trigger and can vary widely in appearance, lacking the classic plaque formation. Acne is characterized by comedones, papules, pustules, and sometimes cysts, but not specifically by erythematous plaques.

Understanding these distinctions is crucial for accurate diagnosis and subsequent management of these skin conditions.