NBDE Oral Pathology and Radiology 5 — Questions and Answers
Question 1: The 'double cortical outline' sign on a panoramic radiograph of the mandibular canal is associated with:
- Inferior alveolar nerve schwannoma (Correct answer)
- Central hemangioma
- Odontogenic keratocyst expanding the canal
- Ameloblastoma involving the canal
Correct answer: Inferior alveolar nerve schwannoma
A schwannoma of the inferior alveolar nerve can expand the mandibular canal, creating a double cortical outline (canal-within-canal) appearance radiographically.
Question 2: Hairy leukoplakia of the tongue in an HIV-positive patient is caused by:
- Candida albicans overgrowth
- Epstein-Barr virus replication in epithelial cells (Correct answer)
- Human papillomavirus type 16
- Herpes simplex virus type 1
Correct answer: Epstein-Barr virus replication in epithelial cells
Oral hairy leukoplakia is caused by EBV replication in epithelial cells of the lateral tongue, producing corrugated white plaques that cannot be wiped off.
Question 3: The radiopaque structure overlying the roots of maxillary premolars most commonly misidentified as periapical pathology is:
- Inferior border of the maxillary sinus
- Zygomatic process of the maxilla (Correct answer)
- Zygoma (malar bone)
- Coronoid process of the mandible
Correct answer: Zygomatic process of the maxilla
The zygomatic process of the maxilla projects as a J-shaped or U-shaped radiopacity over the maxillary first premolar/molar roots and must not be confused with hypercementosis or condensing osteitis.
Question 4: Pemphigus vulgaris of the oral cavity is distinguished from mucous membrane pemphigoid by:
- Suprabasilar acantholysis (intraepithelial clefting) versus subepithelial split (Correct answer)
- Subepidermal bullae in pemphigus versus intraepithelial in pemphigoid
- IgA deposits in pemphigus versus IgG in pemphigoid
- Pemphigus spares the gingiva; pemphigoid involves only the gingiva
Correct answer: Suprabasilar acantholysis (intraepithelial clefting) versus subepithelial split
Pemphigus vulgaris shows suprabasilar acantholysis (loss of cohesion above the basal layer), while mucous membrane pemphigoid features a subepithelial blister below the intact epithelium.
Question 5: A painless, fluctuant, bluish sublingual swelling that displaces the tongue is best diagnosed as:
- Mucocele of a minor salivary gland
- Ranula (retention phenomenon of sublingual gland) (Correct answer)
- Dermoid cyst of the floor of mouth
- Ludwig's angina
Correct answer: Ranula (retention phenomenon of sublingual gland)
A ranula is a mucous retention or extravasation pseudocyst arising from the sublingual gland, presenting as a translucent blue swelling in the floor of the mouth.
Question 6: In interpreting panoramic radiographs, the 'ghost image' artifact appears because:
- Patient movement during exposure blurs the image
- A structure outside the focal trough is imaged bilaterally with a magnified, blurred contralateral projection (Correct answer)
- Metallic restorations scatter X-rays across the film
- Incorrect head positioning tilts the occlusal plane
Correct answer: A structure outside the focal trough is imaged bilaterally with a magnified, blurred contralateral projection
Ghost images form when a radiopaque structure outside the focal trough is projected to the contralateral side at a higher, more blurred, and magnified position due to the rotating X-ray source geometry.
Question 7: Cherubism is a hereditary fibro-osseous condition characterized by all of the following EXCEPT:
- Bilateral jaw expansion beginning in childhood
- Autosomal dominant inheritance with SH3BP2 mutation
- Progressive course into adulthood without spontaneous regression (Correct answer)
- Multilocular radiolucencies replacing jaw bone bilaterally
Correct answer: Progressive course into adulthood without spontaneous regression
Cherubism typically stabilizes at puberty and often undergoes spontaneous partial regression in adulthood, unlike progressive fibro-osseous diseases.
NBDE Oral Pathology and Radiology 5
The 'double cortical outline' sign on a panoramic radiograph of the mandibular canal is associated with: