Final answer:
In medical terms, a thin-walled, elevated fluid-containing lesion less than 1 cm in diameter is called a vesicle. This encapsulated sac with fluid is located just below the skin and in conditions like Impetigo, can evolve into larger, fluid- or pus-filled bumps.
Step-by-step explanation:
A thin-walled, elevated lesion containing fluid that is less than 1 cm in diameter is often described as a vesicle in medical terms. This type of lesion is an encapsulated sac filled with fluid, which can be found just below the upper layers of the skin. Vesicles are different from papules, which are small raised bumps on the skin that do not contain fluid. When vesicles become larger than 1 cm, they are referred to as bullae. Conditions like Impetigo may cause such lesions, leading to the formation of vesicles, pustules, or bullae. Symptoms of Impetigo include the development of vesicles and pustules that rupture and can become encrusted sores with a yellowish crust, typically with exudate draining from the base. In severe cases, lesions can evolve into fluid- or pus-filled bumps on the skin, indicating a more pronounced infection that might require medical attention.