Which type of lesions involve depressions in the skin surface, such as ulcers?

Secondary lesions are classifications that involve changes that occur in the skin as a result of primary lesions or other skin conditions. These can manifest in various ways, including as depressions in the skin surface, which are often seen in ulcers and other similar conditions. Ulcers are specifically areas where the skin has lost its integrity due to the breakdown of tissue, leading to a depressed appearance.

The distinction between primary and secondary lesions lies in their development: primary lesions are the initial reactions of the skin to various triggers, while secondary lesions arise from alterations that develop over time, often in response to the healing processes or continued irritation of primary lesions. Understanding this classification is essential for recognizing and treating various skin conditions effectively.

The other options do not accurately describe the characteristic of having a depressed surface; thus, they do not fit the definition provided in the question. This reinforces the understanding that secondary lesions specifically include such features, making it clear why this option is the right choice.