**Core Concept**
Pemphigus is a group of autoimmune blistering diseases characterized by the formation of autoantibodies against desmoglein proteins, which are components of desmosomes that maintain epithelial cell adhesion. The clinical manifestations of pemphigus depend on the specific autoantibodies involved and the location of the disease.

**Why the Correct Answer is Right**
Pemphigus vulgaris is the most common form of pemphigus, accounting for approximately 70-80% of cases. It is caused by autoantibodies against desmoglein 3, a protein found in the epidermis. The autoantibodies lead to the breakdown of desmoglein 3, resulting in the loss of cell-to-cell adhesion and the formation of blisters. The disease typically presents with oral mucosal lesions, followed by skin lesions.

**Why Each Wrong Option is Incorrect**
**Option A:** Pemphigus foliaceus is a less common form of pemphigus, accounting for approximately 10-20% of cases. It is caused by autoantibodies against desmoglein 1, a protein found in the epidermis, and typically presents with skin lesions.
**Option B:** Bullous pemphigoid is a different autoimmune blistering disease that is caused by autoantibodies against components of the basement membrane zone, rather than desmoglein proteins.
**Option C:** Dermatitis herpetiformis is a chronic skin condition characterized by blisters and itching, but it is not an autoimmune blistering disease like pemphigus.

**Clinical Pearl / High-Yield Fact**
Pemphigus vulgaris is often associated with an increased risk of squamous cell carcinoma, particularly in the oral cavity. Patients with pemphigus should be monitored regularly for signs of oral cancer.

**Correct Answer: C. Bullous pemphigoid is a different autoimmune blistering disease that is caused by autoantibodies against components of the basement membrane zone, rather than desmoglein proteins.