**Core Concept**
Dermatitis herpetiformis is a chronic skin condition characterized by intensely itchy, blistering skin lesions, often located on the elbows, knees, and buttocks. This condition is closely associated with coeliac disease, an autoimmune disorder triggered by gluten ingestion.

**Why the Correct Answer is Right**
The correct answer is incorrect because dermatitis herpetiformis is actually characterized by the presence of IgA antibodies against tissue transglutaminase (TTG), not IgE antibodies. The IgA antibodies play a crucial role in the pathogenesis of the disease, leading to the activation of complement and the subsequent inflammatory response.

**Why Each Wrong Option is Incorrect**
* **Option A:** Dermatitis herpetiformis typically presents with skin lesions on extensor surfaces, but the lesions are not limited to these areas. The condition often involves flexural surfaces as well.
* **Option B:** While most patients with dermatitis herpetiformis do have underlying coeliac disease, this statement is not universally true. Some patients may not have coeliac disease, although they still respond to a gluten-free diet.
* **Option D:** Dapsone is indeed the primary treatment for dermatitis herpetiformis, but it is not the only option. Other treatments, such as sulfasalazine and corticosteroids, may also be used in certain cases.

**Clinical Pearl / High-Yield Fact**
Dermatitis herpetiformis is often considered a skin manifestation of coeliac disease, and a gluten-free diet can lead to significant improvement in symptoms. However, it's essential to note that some patients may not respond to dietary changes alone, and other treatments may be necessary.

**✓ Correct Answer:** C. It is characterized by IgE anitbodies against TTG : Tissue transglutaminase