Massachusetts State Board Esthetics Practice Exam

In dermatology, a cyst is defined as a closed sac containing fluid or other matter. This distinction is crucial because cysts can vary in their contents, which might include serous fluid, pus, or even semi-solid material. The sac-like structure distinguishes cysts from other types of lesions, as they are encapsulated and typically do not heal on their own without intervention.

Understanding what a cyst is helps in identifying various skin conditions. It is important to note that cysts can be found in many tissues and organs throughout the body and can have diverse causes ranging from infections to blockages of ducts. Their nature as closed sacs makes them different from other skin conditions such as blisters, which are generally fluid-filled elevations on the skin's surface, and other descriptors like inflamed areas or discolored spots.

The other choices describe different dermatological terms: a blister filled with pus refers to pustules caused by infections, an area of inflamed skin usually points to conditions like dermatitis, and a flat, discolored area describes macules or papules. Recognizing these definitions reinforces understanding of skin health and the various presentations of skin lesions.