A 60 years old man presented with itchy tense blisters on normal looking skin and uicarial rash. Investigation done for the diagnosis:
**Core Concept**
Pemphigus vulgaris is an autoimmune disease characterized by the formation of intraepidermal blisters due to autoantibodies against desmoglein 3 proteins, which are crucial for cell-to-cell adhesion in the skin.
**Why the Correct Answer is Right**
The patient's symptoms of itchy tense blisters on normal-looking skin and urticarial rash are consistent with pemphigus vulgaris. The disease is caused by the production of autoantibodies against desmoglein 3 proteins, which are essential for the integrity of the epidermal layer. This leads to the breakdown of cell-to-cell adhesion, resulting in the formation of blisters. The presence of urticarial rash is a common feature of pemphigus vulgaris.
**Why Each Wrong Option is Incorrect**
* **Option A:** Pemphigoid is another autoimmune blistering disease, but it primarily affects the basement membrane zone, not the intraepidermal layer.
* **Option B:** Bullous pemphigoid is characterized by tense blisters, but it typically affects the elderly and is often preceded by an urticarial phase.
* **Option C:** Dermatitis herpetiformis is a chronic blistering disease, but it is characterized by intensely itchy, grouped vesicles, often on the elbows, knees, and buttocks.
* **Option D:** Staphylococcal scalded skin syndrome (SSSS) is a bacterial infection that causes blistering, but it primarily affects children and is characterized by a distinctive "scalded skin" appearance.
**Clinical Pearl / High-Yield Fact**
Pemphigus vulgaris is often associated with other autoimmune diseases, such as thyroiditis, Sjögren's syndrome, and lupus erythematosus. A thorough history and physical examination are essential in diagnosing this condition.
**Correct Answer:** C. Bullous pemphigoid.