## Core Concept
Lichen planus (LP) is a chronic inflammatory mucocutaneous condition characterized by an autoimmune response to basal cell layer antigens, leading to damage and apoptosis of these cells. The condition involves T-cell mediated immunity and is often associated with other autoimmune diseases. The clinical presentation includes purplish, itchy, flat bumps.

## Why the Correct Answer is Right
The correct answer option is not directly provided, but based on common associations and characteristics of lichen planus, we can infer that the question seeks an exception to known facts about LP. Typically, lichen planus is known for its association with T-cell immunity, its appearance on skin and mucous membranes, and potential triggers or associations include certain drugs, viral infections (like hepatitis C), and other autoimmune conditions.

## Why Each Wrong Option is Incorrect
Without specific details on options A, B, C, and D, a general approach to evaluating incorrect options regarding lichen planus:
- **Option A:** If this option states a known association or characteristic of LP (e.g., T-cell mediated, associated with hepatitis C), it would be incorrect to say it's an exception.
- **Option B:** Similarly, if this option describes a feature or association of LP (e.g., presence of Wickham's striae, involvement of mucous membranes), it's not the exception.
- **Option C:** If this option presents a commonly recognized fact about LP (e.g., the condition can be triggered by certain drugs), then it's not the correct exception.
- **Option D:** This would be the correct statement if it accurately describes an exception or an incorrect statement about LP.

## Clinical Pearl / High-Yield Fact
A key point to remember is that lichen planus can involve the oral mucosa, leading to **oral lichen planus**, which may present as white patches, erosions, or ulcers. A classic association is with **hepatitis C virus (HCV) infection**, and there's a known risk with certain drugs (e.g., beta-blockers, NSAIDs). A helpful mnemonic or fact is that the "6 Ps" of lichen planus are: **Pruritic**, **Purple**, **Polygonal**, **Planar**, **Papules**, and **Plaques**.

## Correct Answer: D.