What is the term for a lesion characterized by fluid accumulation and inflammation in tissues?

The term that describes a lesion characterized by fluid accumulation and inflammation in tissues is 'exudate.' Exudates are typically the result of inflammation, which leads to the leakage of fluid, proteins, and sometimes cells from blood vessels into surrounding tissues. This process occurs because of an increase in vascular permeability and is often seen in response to infection, injury, or inflammatory conditions.

Exudate is fundamental in the body's response to injury, as it helps to deliver essential immune components to the site of inflammation and aids in the healing process. It is also relevant in distinguishing between different types of fluids associated with pathological conditions, such as transudates, which involve a more passive fluid movement without significant inflammation.

The other terms mentioned have different meanings: a fissure refers to a narrow opening or crack in tissue, a dermatome is a specific area of skin supplied by a single spinal nerve root, and keratolytic pertains to medications or treatments that help remove excess skin or keratin, but none relate directly to the concept of fluid accumulation and inflammation in tissues as exudate does.