What is the defining feature of a vesicle?

A vesicle is characterized specifically as a raised lesion that is less than 1 centimeter in diameter and is filled with clear fluid. This definition aligns perfectly with the characteristics laid out for a vesicle in dermatological terms. The fluid within the vesicle is typically serous and can be easily identified upon inspection, making it distinct from other types of lesions.

In contrast, other options describe different types of skin lesions. For instance, flat lesions greater than 1 centimeter are typically classified as patches, while raised lesions greater than 1 centimeter without fluid would be categorized as nodules or plaques. Additionally, lesions that are greater than 1 centimeter and fluid-filled are referred to as bullae, which differentiate them from vesicles in terms of size and content. Understanding these distinctions is crucial for accurately identifying and classifying skin lesions in practice.