Master the NDEB: High-Yield Practice
Questions with Answers and Step-by-
Step Rationales
1. A 55-year-old male presents with a painless, white, lace-like lesion
bilaterally on the buccal mucosa that cannot be scraped off. What is
the most likely diagnosis?
A. Leukoplakia
B. Oral lichen planus
C. Candidiasis
D. Frictional keratosis
Answer: B
Rationale: Bilateral, reticular (lace-like), non-scrapable white lesions on the
buccal mucosa are pathognomonic for oral lichen planus, an immune-
mediated condition.
2. A patient presents with a rapidly enlarging, painless swelling of the
anterior mandible. Radiographs show a multilocular radiolucency with
a "soap-bubble" appearance. Which lesion is most likely?
A. Ameloblastoma
B. Periapical cyst
C. Simple bone cyst
D. Osteoma
Answer: A
Rationale: Ameloblastoma is a benign but locally aggressive odontogenic
tumor that typically presents as a multilocular radiolucency (soap-bubble or
honeycomb) in the posterior mandible, though it can occur anteriorly.
,3. A deep incisional biopsy of a red, velvety lesion on the floor of the
mouth reveals dysplastic epithelial cells that invade the underlying
connective tissue. What is the definitive diagnosis?
A. Squamous papilloma
B. Verrucous carcinoma
C. Squamous cell carcinoma (SCC)
D. Erythroplakia
Answer: C
Rationale: Invasion of dysplastic cells through the basement membrane
into the connective tissue is the histologic hallmark of invasive squamous
cell carcinoma. Erythroplakia is a clinical description, not a histologic
diagnosis.
4. A patient on long-term phenytoin therapy presents with
generalized, firm, pale pink gingival overgrowth affecting the
interdental papillae. What is the primary histologic feature?
A. Inflammatory cell infiltration
B. Increased collagen deposition in the connective tissue
C. Epithelial acanthosis
D. Granulation tissue formation
Answer: B
Rationale: Phenytoin-induced gingival overgrowth is characterized by
fibrosis and increased deposition of collagen in the connective tissue
stroma, not primarily by inflammation (though secondary inflammation
may occur).
5. A 30-year-old woman has a painless, bluish-purple dome-shaped
swelling on the hard palate. Aspiration yields fresh blood. What is the
most likely diagnosis?
A. Mucocele
B. Hemangioma
,C. Peripheral giant cell granuloma
D. Mucosal neuroma
Answer: B
Rationale: A bluish-purple color and aspiration of fresh blood are classic
signs of a hemangioma, a benign vascular lesion.
6. A patient presents with severe pain in the right maxillary sinus
region, purulent nasal discharge, and dull pain on percussion of the
upper posterior teeth. What is the most likely diagnosis?
A. Acute apical abscess
B. Maxillary sinusitis of odontogenic origin
C. Trigeminal neuralgia
D. Temporomandibular disorder (TMD)
Answer: B
Rationale: The combination of sinus pain, purulent nasal discharge, and
tooth pain (often due to the proximity of roots to the sinus floor) strongly
suggests odontogenic sinusitis.
7. A painless, slow-growing, exophytic mass on the gingiva of a 60-
year-old, with a pebbly surface and a tendency to recur after excision,
is biopsied. Histology shows "invading islands of squamous epithelium
pushing into connective tissue." What is the diagnosis?
A. Peripheral ossifying fibroma
B. Verrucous carcinoma
C. Fibroma
D. Pyogenic granuloma
Answer: B
Rationale: Verrucous carcinoma is a low-grade variant of SCC with a warty
(pebbly) surface, slow growth, and a pushing (rather than infiltrating)
invasive front. It has a strong association with tobacco use.
, 8. A child presents with a painful, rapidly expanding swelling of the
jaw with radiographic "sunburst" periosteal reaction. Which
malignancy is the primary concern?
A. Osteosarcoma
B. Ewing's sarcoma
C. Lymphoma
D. Multiple myeloma
Answer: A
Rationale: Osteosarcoma is the most common primary malignant bone
tumor, and the "sunburst" appearance (periosteal new bone formation
radiating outward) is a classic radiographic feature, especially in younger
patients.
9. A patient experiences sudden, severe, unilateral facial pain along the
maxillary division of the trigeminal nerve triggered by touching the
cheek. What is the first-line medication for this condition?
A. Amoxicillin
B. Carbamazepine
C. Corticosteroids
D. Ibuprofen
Answer: B
Rationale: Classic trigeminal neuralgia (tic douloureux) is treated with
carbamazepine as the first-line anticonvulsant to stabilize neuronal
membranes.
10. Which salivary gland tumor is most commonly found in the parotid
and is the most common benign salivary neoplasm overall?
A. Warthin's tumor
B. Pleomorphic adenoma
C. Mucoepidermoid carcinoma
D. Adenoid cystic carcinoma
Questions with Answers and Step-by-
Step Rationales
1. A 55-year-old male presents with a painless, white, lace-like lesion
bilaterally on the buccal mucosa that cannot be scraped off. What is
the most likely diagnosis?
A. Leukoplakia
B. Oral lichen planus
C. Candidiasis
D. Frictional keratosis
Answer: B
Rationale: Bilateral, reticular (lace-like), non-scrapable white lesions on the
buccal mucosa are pathognomonic for oral lichen planus, an immune-
mediated condition.
2. A patient presents with a rapidly enlarging, painless swelling of the
anterior mandible. Radiographs show a multilocular radiolucency with
a "soap-bubble" appearance. Which lesion is most likely?
A. Ameloblastoma
B. Periapical cyst
C. Simple bone cyst
D. Osteoma
Answer: A
Rationale: Ameloblastoma is a benign but locally aggressive odontogenic
tumor that typically presents as a multilocular radiolucency (soap-bubble or
honeycomb) in the posterior mandible, though it can occur anteriorly.
,3. A deep incisional biopsy of a red, velvety lesion on the floor of the
mouth reveals dysplastic epithelial cells that invade the underlying
connective tissue. What is the definitive diagnosis?
A. Squamous papilloma
B. Verrucous carcinoma
C. Squamous cell carcinoma (SCC)
D. Erythroplakia
Answer: C
Rationale: Invasion of dysplastic cells through the basement membrane
into the connective tissue is the histologic hallmark of invasive squamous
cell carcinoma. Erythroplakia is a clinical description, not a histologic
diagnosis.
4. A patient on long-term phenytoin therapy presents with
generalized, firm, pale pink gingival overgrowth affecting the
interdental papillae. What is the primary histologic feature?
A. Inflammatory cell infiltration
B. Increased collagen deposition in the connective tissue
C. Epithelial acanthosis
D. Granulation tissue formation
Answer: B
Rationale: Phenytoin-induced gingival overgrowth is characterized by
fibrosis and increased deposition of collagen in the connective tissue
stroma, not primarily by inflammation (though secondary inflammation
may occur).
5. A 30-year-old woman has a painless, bluish-purple dome-shaped
swelling on the hard palate. Aspiration yields fresh blood. What is the
most likely diagnosis?
A. Mucocele
B. Hemangioma
,C. Peripheral giant cell granuloma
D. Mucosal neuroma
Answer: B
Rationale: A bluish-purple color and aspiration of fresh blood are classic
signs of a hemangioma, a benign vascular lesion.
6. A patient presents with severe pain in the right maxillary sinus
region, purulent nasal discharge, and dull pain on percussion of the
upper posterior teeth. What is the most likely diagnosis?
A. Acute apical abscess
B. Maxillary sinusitis of odontogenic origin
C. Trigeminal neuralgia
D. Temporomandibular disorder (TMD)
Answer: B
Rationale: The combination of sinus pain, purulent nasal discharge, and
tooth pain (often due to the proximity of roots to the sinus floor) strongly
suggests odontogenic sinusitis.
7. A painless, slow-growing, exophytic mass on the gingiva of a 60-
year-old, with a pebbly surface and a tendency to recur after excision,
is biopsied. Histology shows "invading islands of squamous epithelium
pushing into connective tissue." What is the diagnosis?
A. Peripheral ossifying fibroma
B. Verrucous carcinoma
C. Fibroma
D. Pyogenic granuloma
Answer: B
Rationale: Verrucous carcinoma is a low-grade variant of SCC with a warty
(pebbly) surface, slow growth, and a pushing (rather than infiltrating)
invasive front. It has a strong association with tobacco use.
, 8. A child presents with a painful, rapidly expanding swelling of the
jaw with radiographic "sunburst" periosteal reaction. Which
malignancy is the primary concern?
A. Osteosarcoma
B. Ewing's sarcoma
C. Lymphoma
D. Multiple myeloma
Answer: A
Rationale: Osteosarcoma is the most common primary malignant bone
tumor, and the "sunburst" appearance (periosteal new bone formation
radiating outward) is a classic radiographic feature, especially in younger
patients.
9. A patient experiences sudden, severe, unilateral facial pain along the
maxillary division of the trigeminal nerve triggered by touching the
cheek. What is the first-line medication for this condition?
A. Amoxicillin
B. Carbamazepine
C. Corticosteroids
D. Ibuprofen
Answer: B
Rationale: Classic trigeminal neuralgia (tic douloureux) is treated with
carbamazepine as the first-line anticonvulsant to stabilize neuronal
membranes.
10. Which salivary gland tumor is most commonly found in the parotid
and is the most common benign salivary neoplasm overall?
A. Warthin's tumor
B. Pleomorphic adenoma
C. Mucoepidermoid carcinoma
D. Adenoid cystic carcinoma
