Pathology · patient case question
For Patient B's posterior lateral palatal swelling, each of the following belongs in the differential EXCEPT one. Which is the EXCEPTION?
Patient case: Three soft tissue and bony swellings
Patient: Multiple patients presenting on the same clinic session
Chief complaint: Three separate patients, each with a painless swelling.
History: None of the three has relevant systemic disease.
Findings: Patient A: a firm submucosal nodule on the dorsum of the tongue. Patient B: a firm swelling of the posterior lateral hard palate. Patient C: a small hard bump in the anterior mandibular labial vestibule.
Show answer and explanation
Correct answer: A. Nasopalatine duct (incisive canal) cyst
- A. CORRECT as the exception. The nasopalatine duct cyst is defined by its LOCATION — it arises from epithelial remnants in the incisive canal and therefore sits in the ANTERIOR MIDLINE palate, behind the central incisors, giving the classic heart-shaped radiolucency. A swelling of the POSTERIOR LATERAL palate is anatomically incompatible with it.
- B. Pleomorphic adenoma is the commonest minor salivary gland tumour and its favoured intra-oral site is precisely the posterior lateral hard palate, where minor glands are concentrated. It presents as a firm painless swelling.
- C. A palatal torus is a common developmental bony exostosis of the MIDLINE palate, though larger ones extend laterally, and it belongs in the differential of a hard palatal swelling.
- D. A palatal abscess from a non-vital lateral incisor or a palatal root of a premolar or molar is a routine cause of palatal swelling and must always be excluded by pulp testing.
Note: Always pulp-test the adjacent teeth before assuming a palatal swelling is developmental or neoplastic. An odontogenic abscess is the one that needs treating today.