Radiology · patient case question
What is the finding in Patient A?
Patient case: Two normal structures mistaken for pathology
Patient: Two patients
Chief Complaint: Both attend for routine radiographic examination.
Background: A, 48-year-old female: mandibular anterior teeth all respond normally to cold and are non-tender. B, 9-year-old male: no history of trauma; referred for assessment before orthodontic treatment.
Findings: A: a periapical of the mandibular anteriors shows a well-defined radiopaque RING in the midline near the inferior border, with a small central radiolucency. B: a maxillary occlusal film shows a thin radiolucent LINE running anteroposteriorly in the midline of the palate, with faintly sclerotic margins.
Show answer and explanation
Correct answer: B. The genial tubercles with the lingual foramen
- A. A nutrient canal appears as a narrow linear radiolucency of uniform width running through cancellous bone, not as a dense ring with a central lucency.
- B. CORRECT. The GENIAL TUBERCLES are bony projections on the LINGUAL surface of the mandibular midline giving attachment to the genioglossus and geniohyoid muscles. On a periapical they project as a well-defined RADIOPAQUE RING or doughnut in the midline near the inferior border, with the LINGUAL FORAMEN appearing as the small radiolucency at its centre — the ‘target’ appearance. This is normal anatomy. Its clinical relevance is that the lingual foramen transmits a small artery, which is why HAEMORRHAGE IN THE FLOOR OF THE MOUTH is a recognised and potentially airway-threatening complication of implant placement in the mandibular midline.
- C. A traumatic bone cyst is a considerably larger radiolucency that scallops upward between the roots of vital teeth. It has no dense corticated ring and no central detail.
- D. A periapical granuloma is continuous with the APEX of a NON-VITAL tooth and lacks a dense surrounding ring of bone. These incisors all respond normally to cold, which excludes it.
Note: The mandibular midline on a periapical carries several normal structures that get mistaken for disease: the genial tubercles and lingual foramen, the mental ridge as a pair of radiopaque lines running upward, and the mental fossa as a diffuse radiolucency above it. All are bilateral, symmetrical or midline, and stable across films — which is how they are recognised.