**Question:** A 24-year-old male presents with a hyperpigmented patch over the right upper chest 4 years ago, thick hair over the same with time. Diagnosis is:

A. Vitiligo
B. Pityriasis Rubra Pilaris
C. Hyperpigmentation secondary to trauma or infection
D. Melasma

**Correct Answer:** D. Melasma

**Core Concept:** Melasma is a common hyperpigmentation disorder affecting sun-exposed areas of the skin, particularly in individuals with darker skin types. It is caused by the overproduction of melanin in response to various triggers, including hormonal fluctuations, sunlight, and certain medications.

**Why the Correct Answer is Right:** Melasma is a hyperpigmentation disorder characterized by the overproduction of melanin due to triggers like hormonal changes, sunlight, and specific medications. In this case, the patient presents with a hyperpigmented patch over the right upper chest, which is a typical presentation of melasma. Additionally, the thickening of hair over the same area with time is a clue towards Melasma.

**Why Each Wrong Option is Incorrect:**

A. Vitiligo: Vitiligo is a different pigmentation disorder characterized by depigmentation (loss of melanin), not hyperpigmentation as in Melasma.

B. Pityriasis Rubra Pilaris (PRP): PRP is a group of rare, chronic skin disorders characterized by reddish-orange, scaly patches on the skin. It is not associated with hyperpigmentation and thickening of hair.

C. Hyperpigmentation secondary to trauma or infection: Although trauma and infection can lead to temporary hyperpigmentation, this option does not accurately describe the chronic nature and progression of Melasma.

**Clinical Pearl:** Melasma is typically seen in individuals with darker skin types and can be managed with appropriate treatment options like sun protection, topical agents, and oral medications. However, it is essential to differentiate it from other pigmentation disorders like vitiligo, PRP, and trauma-induced hyperpigmentation.