**Question:** 19 years old girl has multiple papulo pustular erythematous lesions on face and neck, the likely diagnosis is

A. Pityriasis Rosea
B. Acne vulgaris
C. Impetigo
D. Rosacea

**Core Concept:**
The clinical presentation described in the question involves papulo pustular erythematous lesions on the face and neck. This combination of symptoms is indicative of a dermatological condition. In this case, we are considering the most likely diagnosis among Pityriasis Rosea, Acne vulgaris, Impetigo, and Rosacea.

**Why the Correct Answer is Right:**
The correct answer, **D. Rosacea**, is the diagnosis as it is a chronic inflammatory skin disorder that primarily affects the face and presents with papules, pustules, and redness. Rosacea is often associated with flushing and facial sensitivity, which can lead to the formation of papules and pustules. The other options do not match the described clinical presentation:

- **A. Pityriasis Rosea**: Pityriasis Rosea is a self-limiting skin disorder characterized by a single large scaly patch (herpes pustulosa exanthem) and subsequent small papules, pustules, and scarring is not a typical feature.

- **B. Acne vulgaris**: Acne is a disorder involving the sebaceous follicles, primarily affecting the face, chest, and back, which is different from the described presentation on the face and neck. Acne commonly presents with comedones (blackheads and whiteheads) and papules, not pustules.

- **C. Impetigo**: Impetigo is a superficial bacterial infection caused by Staphylococcus and Streptococcus species, typically involving children and causing vesicles, bullae, and frequently presents on the hands and feet. The described presentation does not match impetigo.

**Why Each Wrong Answer is Incorrect:**

- **A. Pityriasis Rosea**: This condition typically presents with a single large scaly patch, known as the "herpes pustulosa exanthem," and subsequent small papules, pustules, and scarring is not a typical feature of Pityriasis Rosea.

- **B. Acne vulgaris**: Acne is a different condition affecting the sebaceous follicles, primarily the face, chest, and back, presenting with comedones (blackheads and whiteheads) and papules, not pustules.

- **C. Impetigo**: Impetigo is a bacterial infection caused by Staphylococcus and Streptococcus species, frequently involving children, and presents with vesicles, bullae, and is typically found on the hands and feet, not the face and neck.

**Clinical Pearl:**

Rosacea is another condition that shares some clinical similarities with acne vulgaris, which is why it can be easily confused with acne. However, distinguishing features between the two conditions help identify the correct diagnosis. Acne typically involves the pilosebaceous units (hair follic