Final answer:
The erythematous patches, papules, and plaques with or without scale described in the question are characteristic of psoriasis vulgaris, a chronic autoimmune skin condition with accelerated skin cell turnover.
Step-by-step explanation:
The symptoms described in the question - poorly defined erythematous patches, papules, and plaques with or without scale - are most indicative of psoriasis vulgaris (Psoriasis). Psoriasis is a chronic autoimmune condition that affects the skin and can present with itchy or sore patches of thick, red skin with silvery scales. These patches can appear on various parts of the body including elbows, knees, scalp, back, face, palms, and feet. Psoriasis is characterized by an accelerated turnover of skin cells due to an interplay between immune cells and skin cells, leading to the buildup and scaling on the skin's surface. While other conditions like atopic dermatitis (eczema) and contact dermatitis can present with similar features, they typically do not have the same kind of scaling seen in psoriasis.