MJDF Oral & Dental Pathology 1 — Questions and Answers
Question 1: What is the histological hallmark of an odontogenic keratocyst (OKC)?
- Thin parakeratinised epithelium (6–8 cell layers) with a basal layer of palisaded cells and a corrugated surface (Correct answer)
- Thick orthokeratinised epithelium
- Dense inflammatory infiltrate throughout wall
- Cholesterol clefts in the lumen
Correct answer: Thin parakeratinised epithelium (6–8 cell layers) with a basal layer of palisaded cells and a corrugated surface
OKCs have a characteristic thin parakeratinised lining with a regular 6–8 cell layer thickness, palisaded basal cells with reverse nuclear polarity, and a corrugated surface — hallmarks used in histological diagnosis.
Question 2: What is the most common benign odontogenic tumour?
- Ameloblastoma (Correct answer)
- Odontoma
- Adenomatoid odontogenic tumour
- Calcifying epithelial odontogenic tumour
Correct answer: Ameloblastoma
Odontoma (compound and complex types) is the most common benign odontogenic tumour or hamartoma; ameloblastoma is the most common true neoplasm of odontogenic origin.
Question 3: What radiographic feature distinguishes a radicular cyst from a periapical granuloma?
- Corticated (well-defined) border around a fluid-filled radiolucency in radicular cyst; granuloma is diffuse (Correct answer)
- Radicular cysts always calcify
- Granulomas are larger than 2 cm always
- Radicular cysts are radiopaque
Correct answer: Corticated (well-defined) border around a fluid-filled radiolucency in radicular cyst; granuloma is diffuse
Radicular cysts typically appear as well-defined radiolucencies with a corticated border; periapical granulomas tend to be smaller, ill-defined, and lack a corticated margin, though histology is required for definitive diagnosis.
Question 4: What is the most common oral manifestation of HIV infection?
- Pseudomembranous candidiasis (oral thrush) and linear gingival erythema (Correct answer)
- Acute necrotising ulcerative gingivitis only
- Oral hairy leukoplakia (EBV) on buccal mucosa
- Kaposi's sarcoma always
Correct answer: Pseudomembranous candidiasis (oral thrush) and linear gingival erythema
Pseudomembranous candidiasis is the most common oral manifestation, often presenting early in HIV disease; oral hairy leukoplakia (lateral tongue) is characteristic, while linear gingival erythema is also specific to HIV-associated periodontal disease.
Question 5: What is the pathological significance of a low-grade mucoepidermoid carcinoma?
- Most common malignant salivary gland tumour; low-grade has good prognosis with surgery (Correct answer)
- Universally fatal within 5 years
- Benign and requires no treatment
- Only affects the sublingual gland
Correct answer: Most common malignant salivary gland tumour; low-grade has good prognosis with surgery
Mucoepidermoid carcinoma is the most common malignant salivary gland tumour; low-grade tumours contain more mucous cells and have an excellent prognosis with complete surgical excision.
Question 6: What is the characteristic microscopic appearance of a pleomorphic adenoma?
- Mixed epithelial and mesenchymal-like stroma (chondromyxoid stroma) with tubular structures (Correct answer)
- Uniform acinar cells with clear cytoplasm
- Inflammatory cells and necrosis
- Pure squamous epithelium
Correct answer: Mixed epithelial and mesenchymal-like stroma (chondromyxoid stroma) with tubular structures
Pleomorphic adenoma (mixed tumour) shows a diverse histology: epithelial ductal structures and myoepithelial cells embedded in a characteristic chondromyxoid stroma, explaining its name.
MJDF Oral & Dental Pathology 1
What is the histological hallmark of an odontogenic keratocyst (OKC)?