Final answer:
A granuloma is a small mass of cells with a necrotic center that develops as part of the immune response. It is formed when macrophages wall off an area of tissue to contain an infection or inflammation.
Step-by-step explanation:
A granuloma is best described as a small mass of cells with a necrotic center, which may develop as part of the immune response. It is formed when immune cells called macrophages wall off an area of tissue to contain an infection or inflammation. Granulomas can develop in various organs and tissues, such as the lungs, liver, or skin. They are typically associated with chronic infections, autoimmune diseases, or exposure to certain substances.