**Core Concept**
Papulo-squamous lesions are characterized by the presence of both papules (raised, solid lesions) and scales, often resulting from an abnormal keratinization process. These lesions can arise from various dermatological conditions, including eczematous, psoriatic, and fungal infections.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of these lesions. Papulo-squamous lesions typically result from an abnormal keratinization process, leading to the accumulation of scales. This process is often associated with conditions such as psoriasis, eczema, and seborrheic dermatitis. These conditions involve an abnormal proliferation of keratinocytes, which can lead to the formation of papules and scales.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is a common cause of papulo-squamous lesions. Psoriasis is a chronic autoimmune condition characterized by an abnormal keratinization process, leading to the formation of papules and scales.
**Option B:** This option is incorrect because it is a common cause of papulo-squamous lesions. Eczema, also known as atopic dermatitis, is a condition characterized by an abnormal immune response, leading to an abnormal keratinization process and the formation of papules and scales.
**Option C:** This option is incorrect because it is a common cause of papulo-squamous lesions. Seborrheic dermatitis is a condition characterized by an abnormal keratinization process, leading to the formation of papules and scales, particularly on the scalp and face.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that papulo-squamous lesions often result from an abnormal keratinization process, which can be triggered by various factors, including autoimmune conditions, allergic reactions, and fungal infections. It's essential to identify the underlying cause of these lesions to provide effective treatment.

**Correct Answer: D.**