**Core Concept**
Koeppe nodules are a type of inflammatory lesion that occurs in the eyes, specifically in the anterior segment of the iris. They are associated with various conditions, including sarcoidosis, tuberculosis, and other granulomatous diseases.

**Why the Correct Answer is Right**
Koeppe nodules are characterized by the presence of granulomatous inflammation, which is a type of chronic inflammation that involves the activation of immune cells, such as macrophages and T lymphocytes. These cells accumulate in the iris and form nodules, which can be seen on ophthalmological examination. The exact mechanism of Koeppe nodule formation is not fully understood, but it is believed to involve the interaction between immune cells and the iris tissue.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Koeppe nodules are not typically associated with allergic reactions or atopic conditions.
**Option B:** This option is incorrect because Koeppe nodules are not a type of infectious lesion, although they can be associated with infections such as tuberculosis.
**Option C:** This option is incorrect because Koeppe nodules are not a type of neoplastic lesion, although they can be associated with various systemic diseases.

**Clinical Pearl / High-Yield Fact**
Koeppe nodules are an important diagnostic clue in patients with sarcoidosis, a systemic granulomatous disease that can affect multiple organs, including the eyes, lungs, and skin. The presence of Koeppe nodules in the eyes can be a sign of underlying sarcoidosis, and patients with this condition should be evaluated for systemic symptoms and other manifestations of the disease.

**Correct Answer:** C.