Radicular cyst. Radicular (periapical) cysts are squamous-lined cysts. Typically, they show inflammatory cell infiltrates in the wall and in the lining, as seen here. The type of inflammatory cell can be chronic, acute, or a mixture. There may be little inflammation. The radiographic appearance and clinical history are important to the diagnosis of radicular cyst as dentigerous cysts can become inflamed as well and mimic a radicular cyst histologically. Associating a periapical squamous-lined cyst that is inflamed with a carious tooth helps confirm the diagnosis.