MFDS Oral Pathology 2

Question 1

What is the significance of epithelial dysplasia in a biopsy of an oral white patch, and which histological features indicate severe dysplasia?

Accepted Answer

Dysplasia indicates disordered epithelial maturation with potential for malignant transformation; severe dysplasia features include drop-shaped rete ridges, abnormal mitoses in the upper epithelium, loss of polarity, and marked nuclear pleomorphism extending into the upper third

Answer

Epithelial dysplasia represents disordered cell maturation and is the most important predictor of malignant transformation in potentially malignant oral lesions. Features include architectural changes (irregular rete ridges, loss of normal maturation, bulbous drop-shaped rete processes) and cytological changes (nuclear pleomorphism, increased nuclear-cytoplasmic ratio, abnormal mitoses, loss of polarity). Severe dysplasia involves the full thickness of the epithelium and carries the highest transformation risk.

Question 2

A patient presents with multiple jaw cysts. Genetic testing reveals a mutation in the PTCH1 gene. What syndrome is this patient likely to have?

Accepted Answer

Gorlin-Goltz syndrome (naevoid basal cell carcinoma syndrome)

Answer

Gorlin-Goltz syndrome (naevoid basal cell carcinoma syndrome) is an autosomal dominant condition caused by mutations in the PTCH1 tumour suppressor gene on chromosome 9q22. Features include multiple odontogenic keratocysts (often presenting in the first decade), multiple basal cell carcinomas (especially after puberty), skeletal anomalies (bifid ribs, spina bifida occulta), calcification of the falx cerebri, palmar/plantar pits, and medulloblastoma in childhood.

Question 3

What are the characteristic histological features of oral verrucous carcinoma?

Accepted Answer

A well-differentiated, exophytic, broad-based squamous neoplasm with a verrucous surface, pushing (rather than infiltrating) deep margins, minimal cytological atypia, and keratin-filled clefts

Answer

Verrucous carcinoma is a variant of well-differentiated squamous cell carcinoma with a verrucous (warty) exophytic growth pattern. Key histological features include broad, club-shaped rete ridges that push into the connective tissue with a well-defined deep margin (rather than irregular infiltration), minimal cytological atypia, and keratin-filled clefts ('church spire' keratinisation). Despite being locally destructive, it rarely metastasises. Diagnosis requires a deep biopsy to demonstrate the pushing margins.

Question 4

A biopsy from a gingival swelling in a 25-year-old female shows a proliferation of multinucleated giant cells in a vascular stroma. Serum calcium and parathyroid hormone levels are normal. What is the most likely diagnosis?

Accepted Answer

Peripheral giant cell granuloma

Answer

A peripheral giant cell granuloma (PGCG) is a reactive lesion arising exclusively from the gingiva or edentulous alveolar ridge. It contains numerous multinucleated giant cells (osteoclast-like) in a vascular connective tissue stroma with haemosiderin deposits. It is histologically indistinguishable from the central giant cell granuloma and the brown tumour of hyperparathyroidism, hence the importance of checking serum calcium and PTH levels to exclude hyperparathyroidism. Normal biochemistry confirms PGCG.

Question 5

What is the WHO classification of salivary gland tumours with regard to mucoepidermoid carcinoma, and what determines its grading?

Accepted Answer

It is the most common malignant salivary gland tumour, graded as low, intermediate, or high based on the proportion of cystic spaces, mucous cells, epidermoid cells, neural invasion, necrosis, and mitotic rate

Answer

Mucoepidermoid carcinoma is the most common malignant salivary gland tumour (and the most common salivary malignancy in children). It is graded into low, intermediate, and high grade based on histological features: low-grade tumours are predominantly cystic with abundant mucous cells; high-grade tumours are predominantly solid with epidermoid cells, frequent mitoses, neural invasion, and necrosis. Five-year survival ranges from >90% for low-grade to <50% for high-grade tumours.

MFDS Part 1 Practice Test

MFDS Part 1 Practice Test

MFDS Oral Pathology 2