AGD Oral Pathology and Diagnosis 5 — Questions and Answers
Question 1: A young patient presents with multiple jaw cysts, bifid ribs, calcification of the falx cerebri, and skeletal anomalies. What is the underlying gene mutation?
- APC tumor suppressor gene
- PTCH1 (patched) gene mutation (Correct answer)
- STK11 gene mutation
- TP53 tumor suppressor gene
Correct answer: PTCH1 (patched) gene mutation
Nevoid basal cell carcinoma syndrome (Gorlin-Goltz syndrome) is caused by PTCH1 gene mutations in the hedgehog signaling pathway and features multiple odontogenic keratocysts, basal cell carcinomas, and skeletal anomalies.
Question 2: Which of the following features distinguishes fibrous dysplasia from ossifying fibroma radiographically?
- Fibrous dysplasia has well-defined corticated borders; ossifying fibroma does not
- Fibrous dysplasia blends imperceptibly with normal bone; ossifying fibroma has a well-defined border (Correct answer)
- Fibrous dysplasia causes root resorption; ossifying fibroma displaces teeth
- Fibrous dysplasia appears as a mixed lesion; ossifying fibroma is purely radiolucent
Correct answer: Fibrous dysplasia blends imperceptibly with normal bone; ossifying fibroma has a well-defined border
Fibrous dysplasia merges imperceptibly with surrounding normal bone (poorly defined borders), while ossifying fibroma is encapsulated with a well-defined, often corticated border.
Question 3: A patient on long-term bisphosphonate therapy for osteoporosis undergoes tooth extraction. Four months later, exposed necrotic bone is visible at the extraction site. What is the correct diagnosis?
- Osteomyelitis
- Osteoradionecrosis
- Medication-related osteonecrosis of the jaw (MRONJ) (Correct answer)
- Sequestrum from dry socket
Correct answer: Medication-related osteonecrosis of the jaw (MRONJ)
MRONJ is defined as exposed or necrotic bone in the jaw that has not healed within 8 weeks in a patient with current or previous antiresorptive therapy without prior radiation to the jaws.
Question 4: Which of the following conditions is associated with trismus, medial pterygoid fibrosis, and a burning sensation of the oral mucosa with betel nut use?
- Oral submucous fibrosis (Correct answer)
- Scleroderma
- Chronic hyperplastic candidiasis
- Plaque-type lichen planus
Correct answer: Oral submucous fibrosis
Oral submucous fibrosis is a potentially malignant disorder caused by areca nut (betel quid) chewing, characterized by progressive fibrosis leading to trismus and mucosal rigidity.
Question 5: A child presents with a dome-shaped, painless swelling on the anterior palate near the midline. Radiograph reveals a heart-shaped radiolucency between the roots of the maxillary central incisors. What is the diagnosis?
- Globulomaxillary cyst
- Nasopalatine duct cyst (Correct answer)
- Median palatine cyst
- Nasolabial cyst
Correct answer: Nasopalatine duct cyst
The nasopalatine duct cyst is the most common non-odontogenic cyst of the oral cavity, presenting as a heart-shaped radiolucency between the central incisors near the incisive foramen.
Question 6: Which of the following is the MOST common benign mesenchymal tumor of the oral cavity?
- Neurofibroma
- Lipoma
- Fibroma (focal fibrous hyperplasia) (Correct answer)
- Hemangioma
Correct answer: Fibroma (focal fibrous hyperplasia)
The fibroma (focal fibrous hyperplasia) is the most common soft tissue tumor of the oral cavity, representing a reactive hyperplasia to local irritation rather than a true neoplasm.
Question 7: A 50-year-old presents with xerostomia, keratoconjunctivitis sicca, and bilateral parotid gland enlargement. Lip biopsy shows focal lymphocytic sialadenitis with a focus score of ≥1. What is the diagnosis?
- Sarcoidosis
- IgG4-related disease
- Sjögren syndrome (Correct answer)
- Mikulicz disease
Correct answer: Sjögren syndrome
Sjögren syndrome is diagnosed by the triad of dry eyes, dry mouth, and positive minor salivary gland biopsy (focus score ≥1 lymphocytic aggregate per 4mm² of glandular tissue).
AGD Oral Pathology and Diagnosis 5
A young patient presents with multiple jaw cysts, bifid ribs, calcification of the falx cerebri, and skeletal anomalies.
What is the underlying gene mutation?