**Core Concept**
Lichen planus (LP) is a chronic inflammatory mucocutaneous disease characterized by an immune-mediated response, involving both T cells and autoantibodies. The exact pathogenesis is not fully understood, but it is believed to result from a combination of genetic predisposition, environmental triggers, and autoimmune mechanisms.

**Why the Correct Answer is Right**
Lichen planus is a T-cell mediated autoimmune disease, with a key role played by CD8+ T cells. The immune response is directed against basal cell layer antigens, leading to apoptosis of these cells and subsequent activation of keratinocytes and other immune cells. This results in the characteristic clinical and histological features of LP, including a lichenoid interface dermatitis.

**Why Each Wrong Option is Incorrect**
**Option A:** Lichen planus is primarily an IgG-mediated disease.
* Incorrect because LP is primarily a T-cell mediated disease, not an IgG-mediated one.

**Option B:** Lichen planus is characterized by a dense infiltrate of eosinophils.
* Incorrect because while eosinophils may be present in some cases of LP, the primary infiltrate is composed of T cells and histiocytes.

**Option C:** Lichen planus is associated with a higher risk of developing squamous cell carcinoma.
* Incorrect because LP is associated with an increased risk of developing oral hairy leukoplakia and oral lichenoid lesions, but not squamous cell carcinoma.

**Option D:** Lichen planus is typically a self-limiting condition.
* Incorrect because while some cases of LP may resolve spontaneously, many others require treatment and can be chronic.

**Clinical Pearl / High-Yield Fact**
Lichen planus is often associated with other autoimmune diseases, including psoriasis, vitiligo, and autoimmune hepatitis.

**Correct Answer:** D. Lichen planus is typically a self-limiting condition.