Oral and Maxillofacial Pathology and Oral Oncology
Domain 4 tests risk assessment, biopsy strategy, and staging of oral potentially malignant disorders and oral cancer, plus recognition of common salivary and odontogenic tumors. The exam emphasizes what changes management: dysplasia, depth of invasion, margins, and neck status.
Oral potentially malignant disorders
- Leukoplakia, erythroplakia, oral submucous fibrosis, actinic cheilitis, palatal lesions in reverse smokers, and oral lichen planus are recognized; erythroplakia carries the highest risk.
- Dysplasia is graded as mild, moderate, severe, or carcinoma in situ. Grade predicts risk but not perfectly; clinical appearance and site matter.
- Risk factors include tobacco, alcohol, betel quid, and HPV for oropharyngeal cancer.
Oral squamous cell carcinoma
- Common sites are lateral tongue and floor of mouth.
- Presentation: persistent ulcer, induration, pain, bleeding, fixation, and cervical lymphadenopathy.
- Biopsy is incisional, avoids necrotic center, and includes adjacent normal tissue.
- TNM 8th edition incorporates depth of invasion into T staging and extranodal extension into N staging.
- Clear margins are generally more than 5 mm; close margins increase recurrence risk.
- Field cancerization explains second primary tumors.
Salivary and odontogenic lesions
- Pleomorphic adenoma is the most common parotid tumor; painless and prone to recurrence if ruptured.
- Mucoepidermoid carcinoma is graded low or high; adenoid cystic carcinoma has perineural invasion.
- Ameloblastoma occurs in the posterior mandible with a soap-bubble appearance.
- Odontogenic keratocyst may be associated with Gorlin syndrome.
- Dentigerous cyst surrounds the crown of an impacted tooth.
Worked example
A 62-year-old smoker has a 3-month nonhealing lateral tongue ulcer, 2 cm, indurated, with a fixed submandibular node. Incisional biopsy shows squamous cell carcinoma. The tumor is staged with imaging and neck assessment; depth of invasion and extranodal extension determine T and N categories. Referral to a head and neck multidisciplinary team is appropriate.
Traps that cost marks
- Watching and waiting on erythroplakia.
- Taking a superficial punch biopsy that misses invasive disease.
- Failing to palpate and image the neck.
- Not recording depth of invasion.
- Dismissing leukoplakia in a patient who does not smoke.