Which description best matches the pathophysiology of a periapical or radicular cyst?

• A. A cavity lined with epithelium and surrounded by granulomatous tissue.
• B. A cavity lined with bone.
• C. A fluid-filled sac with no epithelial lining.
• D. A solid fibrous mass without a cavity.

Answer: (A)

Radicular (periapical) cysts form when chronic inflammation from a necrotic pulp stimulates epithelial rests in the periodontal ligament to proliferate and create a true cystic cavity. The wall of that cavity is connective tissue often rich in inflammatory cells, with the lumen lined by epithelium. This combination—an actual cavity that has an epithelial lining and a surrounding inflammatory/granulation tissue wall—best matches the description.

Other options describe features that don’t fit a true cyst: a cavity lined by bone isn’t how a radicular cyst forms; a fluid-filled sac without an epithelial lining would be a pseudocyst; and a solid fibrous mass lacks a central cavity with epithelial lining.