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Pathology · patient case question

How should Patient A's lesion be interpreted?

Patient case: Two radiolucencies that are not what their names suggest

Patient: Two patients

Chief Complaint: A: incidental finding at a new patient examination. B: incidental finding on a panoramic taken before orthodontic assessment.

Background: A, 34-year-old male: asymptomatic, no history of trauma or caries in the region. B, 25-year-old female: healthy, no extractions ever performed.

Findings: A: an inverted pear-shaped radiolucency between the roots of the maxillary lateral incisor and canine, with the roots divergent. BOTH teeth respond normally to cold and electric pulp testing. B: a well-defined corticated radiolucency in the posterior mandible occupying the position where a third molar never developed. No tooth is present and none is visible elsewhere.

  1. It is a normal anatomical variant requiring no investigation
  2. It is a radicular cyst arising from the lateral incisor
  3. It is a fissural cyst arising from epithelium trapped at the fusion of the globular and maxillary processes
  4. It is globulomaxillary in LOCATION, but this is not a distinct entity — the diagnosis must be established by biopsy
Show answer and explanation

Correct answer: D. It is globulomaxillary in LOCATION, but this is not a distinct entity — the diagnosis must be established by biopsy

  • A. An expanding radiolucency between two vital teeth always requires investigation. Nothing about this site makes a lucency normal.
  • B. A radicular cyst requires a NON-VITAL tooth. Both teeth here respond normally to pulp testing, which is precisely why vitality testing is the first investigation — it excludes the commonest cause in a single step.
  • C. This is the classic teaching that has been ABANDONED. The globular and maxillary processes do not fuse in a manner that traps epithelium at this site, and the fissural theory is no longer accepted.
  • D. CORRECT. ‘Globulomaxillary cyst’ describes a LOCATION, not a diagnosis, and it has been removed from current classification. Lesions found in this site prove on histology to be ODONTOGENIC — radicular cyst, lateral periodontal cyst, odontogenic keratocyst, periapical granuloma, odontogenic myxoma or central giant cell granuloma. The inverted-pear shape with divergent roots is a description of appearance, not a diagnosis. The sequence is therefore: pulp test both teeth, then biopsy.

Note: The ‘median mandibular cyst’ has met the same fate and for the same reason. The NASOPALATINE DUCT CYST, by contrast, remains an accepted developmental non-odontogenic cyst — it arises from remnants of the nasopalatine duct, appears as a round or heart-shaped midline lucency at or just behind the incisive foramen, and is diagnosed when it exceeds about 6 mm or produces symptoms or expansion.

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