Pathology · patient case question
A separate patient presents with a painless bump on the gingiva. Tooth #7 gives no response to cold, is not tender to percussion, and shows a well-defined periapical radiolucency. Biopsy shows chronic inflammatory infiltrate, cholesterol clefts and a lining of non-keratinised stratified squamous epithelium. What is the diagnosis?
Patient case: Facial swelling with a radiolucency at the distal root of #18
Patient: Female, 39 years old
Chief complaint: “My face is swollen.”
History: Currently taking amoxicillin prescribed by an urgent care clinic.
Findings: Distal-occlusal decay on tooth #18 with vestibular oedema and active purulent drainage. A well-circumscribed radiolucency is associated with the distal root. Tooth #18 does not respond to cold. A biopsy of the excised lesion is reported as a radicular cyst.
Show answer and explanation
Correct answer: A. Periapical cyst
- A. CORRECT. The decisive histologic feature is the EPITHELIAL LINING. A periapical (radicular) cyst is defined by a cavity lined with non-keratinised stratified squamous epithelium, with a wall of chronically inflamed fibrous connective tissue containing cholesterol clefts and, often, Rushton bodies and haemosiderin. Cholesterol clefts come from breakdown of red cell membranes within the lesion.
- B. A periapical granuloma is granulation tissue with chronic inflammatory cells and NO epithelial lining. That is the whole distinction, and it can only be made histologically — the two are indistinguishable radiographically.
- C. A parulis is the soft-tissue swelling at the mouth of a sinus tract, composed of granulation tissue. It has no cystic cavity and no epithelial lining beyond the surface mucosa.
- D. A periapical scar is dense fibrous tissue that persists after healing, with minimal inflammation, no epithelium and no cholesterol clefts. It follows treatment rather than preceding it.
Note: Both lesions require a NON-VITAL tooth. Treatment for both is root canal treatment first; surgery is reserved for lesions that fail to resolve.