**Core Concept**
Dermatitis herpetiformis is a chronic skin condition characterized by intensely itchy, grouped vesicles or blisters, typically appearing on the buttocks, elbows, knees, and scalp. It is associated with celiac disease, an autoimmune disorder triggered by gluten sensitivity.

**Why the Correct Answer is Right**
The patient's symptoms are consistent with dermatitis herpetiformis, which is known for its intensely itchy, grouped vesicles. The condition is often exacerbated by exposure to gluten-containing foods, such as wheat. The pathophysiology involves an autoimmune response to gluten, leading to the formation of IgA antibodies against tissue transglutaminase (tTG). This reaction causes inflammation and blistering in the skin. The condition is often associated with celiac disease, which is also triggered by gluten sensitivity.

**Why Each Wrong Option is Incorrect**
**Option A:** Herpes simplex is a viral infection that causes vesicular eruptions, but it is not typically associated with gluten exposure and does not present with intensely itchy lesions.

**Option C:** Pemphigus vulgaris is an autoimmune blistering disease that affects the skin and mucous membranes, but it is not typically associated with gluten sensitivity and does not present with intensely itchy lesions.

**Option D:** Bullous impetigo is a bacterial infection that causes blistering, but it is not typically associated with gluten exposure and does not present with intensely itchy lesions.

**Clinical Pearl / High-Yield Fact**
Dermatitis herpetiformis is a classic example of a skin condition associated with an underlying systemic disease (celiac disease). It is essential to consider gluten sensitivity in the differential diagnosis of intensely itchy, grouped vesicles.

**✓ Correct Answer: B. Dermatitis herpetiformis**