Final answer:
A fluid-filled skin lesion that is less than 1 cm in size is called a Vesicle. The condition impetigo can cause such vesicles to form on the skin, often around the nose and mouth.
Step-by-step explanation:
A skin lesion which is fluid-filled and less than 1 cm in size is called a Vesicle. Vesicles are small encapsulated sacs filled with fluid, commonly seen in conditions like impetigo. Bullae are similar but are usually larger than 5 mm in diameter. Papules are small raised bumps on the skin without fluid, and macules are smooth spots of discoloration. The skin infection impetigo is an example that causes the formation of vesicles, pustules (pus-filled bumps), and possibly bullae, often around the nose and mouth.