NBDE Oral Pathology and Radiology Questions and Answers — Questions and Answers
Question 1: A panoramic radiograph of a 25-year-old male reveals a well-defined, unilocular radiolucency in the posterior mandible, extending anteroposteriorly along the bone with minimal buccolingual expansion. The lesion appears to scallop between the roots of the adjacent teeth, but no significant root resorption is noted. Which of the following is the most likely diagnosis?
- Ameloblastoma
- Odontogenic Keratocyst (OKC) (Correct answer)
- Radicular Cyst
- Dentigerous Cyst
Correct answer: Odontogenic Keratocyst (OKC)
The radiographic features described—a unilocular radiolucency with a tendency for anteroposterior growth, minimal expansion, and scalloping between roots without significant resorption—are highly characteristic of an Odontogenic Keratocyst (OKC). Ameloblastomas are more likely to be multilocular and cause significant bone expansion and root resorption. A radicular cyst is associated with a non-vital tooth, and a dentigerous cyst is always associated with the crown of an impacted tooth.
Question 2: A biopsy of a painful oral erosion is performed. Histopathologic examination reveals an intraepithelial split just above the basal cell layer, with the basal cells remaining attached to the underlying connective tissue, creating a 'tombstone' appearance. Cytology shows rounded acantholytic keratinocytes (Tzanck cells). What is the most likely diagnosis?
- Pemphigus vulgaris (Correct answer)
- Bullous pemphigoid
- Erythema multiforme
- Lichen planus
Correct answer: Pemphigus vulgaris
The histopathologic finding of a suprabasilar intraepithelial separation with basal cells forming a 'tombstone row' and the presence of acantholytic Tzanck cells are pathognomonic for Pemphigus Vulgaris. Bullous pemphigoid shows a subepidermal split, and both Erythema multiforme and Lichen planus have different characteristic histologic features without acantholysis.
Question 3: A 28-year-old female patient presents with a chief complaint of recurrent, painful oral ulcers. Clinical examination reveals multiple aphthous-like ulcers, diffuse mucosal erythema, and a 'cobblestone' appearance of the buccal mucosa. Her medical history is significant for intermittent abdominal pain and diarrhea. Which systemic condition is most likely associated with these oral findings?
- Behçet's syndrome
- Systemic Lupus Erythematosus
- Crohn's disease (Correct answer)
- Pemphigus vulgaris
Correct answer: Crohn's disease
The combination of aphthous-like ulcers, cobblestone mucosa, and linear ulcerations is highly suggestive of oral manifestations of Crohn's disease, an inflammatory bowel disease. These oral signs can sometimes precede the gastrointestinal symptoms. While Behçet's syndrome also presents with oral ulcers, the cobblestone appearance is more specific to Crohn's disease.
Question 4: A panoramic radiograph of a 16-year-old male shows an ill-defined, mixed radiolucent-radiopaque lesion in the body of the mandible. Fine spicules of bone are seen radiating from the surface of the lesion, creating a 'sunburst' or 'sunray' appearance. This radiographic finding is most characteristic of which of the following malignancies?
- Squamous cell carcinoma
- Chondrosarcoma
- Multiple myeloma
- Osteosarcoma (Correct answer)
Correct answer: Osteosarcoma
The 'sunburst' or 'sunray' appearance is a classic, though not exclusive, radiographic sign of osteosarcoma. It represents spicules of new bone being formed by the malignant tumor cells perpendicular to the cortical surface as the lesion expands. While other conditions can have similar features, this appearance is most strongly associated with osteosarcoma of the jaw.
Question 5: A 60-year-old patient presents with a solitary, asymptomatic, blue-black, flat lesion on the gingiva adjacent to a large amalgam restoration. A periapical radiograph of the area reveals no bone involvement but may show tiny, radiopaque fragments. What is the most likely diagnosis?
- Melanotic macule
- Amalgam tattoo (Correct answer)
- Melanocytic nevus
- Malignant melanoma
Correct answer: Amalgam tattoo
The clinical presentation of a blue-black macule on the gingiva adjacent to an amalgam restoration is the classic description of an amalgam tattoo. It is caused by the accidental implantation of amalgam particles into the soft tissue. While other pigmented lesions must be considered in a differential diagnosis, the proximity to the restoration is a key diagnostic clue. A radiograph can sometimes confirm the diagnosis if the embedded particles are large enough to be visible.
Question 6: Which of the following best describes the core principle of ALARA in dental radiology?
- Using the highest possible exposure settings to ensure a perfect image.
- Taking radiographs on a fixed schedule, regardless of clinical findings.
- Minimizing radiation dose to the patient while still obtaining a diagnostically acceptable image. (Correct answer)
- Mandating the use of a lead apron for extraoral imaging only.
Correct answer: Minimizing radiation dose to the patient while still obtaining a diagnostically acceptable image.
ALARA is an acronym for 'As Low As Reasonably Achievable.' This is a fundamental radiation safety principle that means every reasonable effort should be made to keep radiation exposure to patients and staff as low as possible while still achieving the necessary diagnostic information. This involves justifying the need for radiographs, using the lowest effective dose, and proper technique to avoid retakes.
NBDE Oral Pathology and Radiology Questions and Answers
A panoramic radiograph of a 25-year-old male reveals a well-defined, unilocular radiolucency in the posterior mandible, extending anteroposteriorly along the bone with minimal buccolingual expansion.
The lesion appears to scallop between the roots of the adjacent teeth, but no significant root resorption is noted.
Which of the following is the most likely diagnosis?