**Question:** Hypopigmented patches present in –

**Core Concept**
Hypopigmented patches are areas of skin that are lighter than the surrounding skin due to a reduction in melanin production or deposition. This can be caused by various factors, including genetic disorders, infections, and autoimmune diseases.

**Why the Correct Answer is Right**
The correct answer is **Pityriasis Alba**. Pityriasis Alba is a common skin condition characterized by hypopigmented patches on the face, typically in children and young adults. It is thought to be caused by a combination of factors, including dry skin, sun exposure, and an imbalance of the skin's natural pH. The condition is often associated with an increase in the enzyme **tyrosinase**, which is responsible for converting the amino acid tyrosine into melanin.

**Why Each Wrong Option is Incorrect**
**Option A:** Vitiligo - This is an autoimmune disease that causes white patches on the skin due to the destruction of melanocytes. While it does result in hypopigmentation, it is not the correct answer for this question.

**Option B:** Erythema Multiforme - This is a skin condition characterized by target-shaped lesions, typically on the hands and feet. It is an autoimmune reaction and does not typically present with hypopigmentation.

**Option C:** Pityriasis Versicolor - This is a fungal infection that causes patches of discoloration on the skin, but it typically results in hyperpigmentation, not hypopigmentation.

**Clinical Pearl / High-Yield Fact**
Pityriasis Alba is often associated with atopic dermatitis, and patients with this condition are more likely to develop other atopic conditions, such as asthma and allergies.

**Correct Answer: A. Pityriasis Alba**