**Core Concept**
Atopic dermatitis, also known as **atopic eczema**, is a chronic inflammatory skin condition characterized by dry, itchy, and scaly skin. The diagnosis of atopic dermatitis is primarily based on **clinical presentation** and **history**, rather than specific laboratory tests. A thorough understanding of **dermatological conditions** is essential for accurate diagnosis.

**Why the Correct Answer is Right**
**Clinical examination** is the correct answer because it involves a thorough assessment of the patient's skin, including the appearance, distribution, and severity of lesions. A **detailed medical history** and **physical examination** can help identify characteristic features of atopic dermatitis, such as **pruritus**, **xerosis**, and **lichenification**. This approach allows clinicians to differentiate atopic dermatitis from other skin conditions.

**Why Each Wrong Option is Incorrect**
**Option A:** A patch test is used to diagnose **contact dermatitis**, not atopic dermatitis. While patch testing can identify specific allergens, it is not a primary diagnostic tool for atopic dermatitis.
**Option B:** A Wood lamp is used to diagnose **fungal** or **bacterial infections**, not atopic dermatitis. The Wood lamp emits ultraviolet light, which can help identify certain microorganisms.
**Option D:** IgE is an **immunoglobulin** involved in **allergic reactions**, and while elevated IgE levels are often seen in atopic dermatitis, this test is not specific or sensitive enough for diagnosis.

**Clinical Pearl / High-Yield Fact**
Atopic dermatitis is a common condition that can have a significant impact on quality of life. Clinicians should be aware of the **diagnostic criteria**, including **pruritus**, **eczematous lesions**, and **personal or family history of atopy**. A thorough clinical examination is essential for accurate diagnosis and management.

**✓ Correct Answer: C. Clinical examination**