What is a nodule?

A nodule is defined as a small, circumscribed swelling that is typically protruding above the skin's surface. This description aligns with the characteristics of a nodule, which can be solid or cystic and is usually found in the dermis or subcutaneous tissue. Nodules can vary in size and are often palpable, making them distinct from other types of skin lesions.

The other options describe different types of skin lesions or conditions that do not match the definition of a nodule. For instance, an elevation filled with pus would be categorized as a pustule, and a thin-walled lesion with clear fluid would be recognized as a vesicle or blister. A deep burn resulting from fire refers to thermal injury and is not classified as a nodule. Therefore, the correct understanding and terminology of a nodule is crucial for accurate coding and medical documentation.