A lump behind the tonsil

Correct answer: A. Human papillomavirus type 16

• A. Correct. HPV-16 accounts for the large majority of oropharyngeal squamous cell carcinomas, which arise in the tonsillar crypts and base of tongue. The E6 and E7 oncoproteins inactivate p53 and retinoblastoma protein. The typical patient is younger, a non-smoker, and presents with nodal disease from a small primary, exactly as here.
• B. HIV increases the incidence of Kaposi sarcoma, non-Hodgkin lymphoma and cervical carcinoma through immunosuppression, but it is not the direct oncogenic driver of tonsillar carcinoma.
• C. Epstein-Barr virus is the virus of nasopharyngeal carcinoma, Burkitt lymphoma and oral hairy leukoplakia, and the nasopharynx is a different site from the oropharynx.
• D. Herpes simplex type 1 causes primary herpetic gingivostomatitis and recurrent herpes labialis. It has no established causal role in this carcinoma.

Correct answer: C. Oropharynx

• A. Floor of mouth carcinoma is strongly linked to tobacco and alcohol. It sits in the oral cavity proper rather than the oropharynx.
• B. The hard palate is an uncommon site for squamous cell carcinoma and is more associated with salivary gland tumours and with reverse smoking practices.
• C. Correct. HPV-associated oropharyngeal cancer has overtaken cervical cancer as the most common HPV-related malignancy in the United States. Incidence has risen in men in particular, while tobacco-driven oral cavity cancer has been falling. The prognosis is notably better than for HPV-negative disease.
• D. Lower lip cancer is driven by ultraviolet exposure, which is why it affects outdoor workers and is preceded by actinic cheilitis.

Correct answer: A. Adenoid cystic carcinoma

• A. Correct. Adenoid cystic carcinoma shows a cribriform pattern of basaloid cells surrounding pseudocystic spaces filled with basement membrane material, giving the swiss cheese appearance. Its defining behaviour is perineural invasion, which produces pain and facial numbness and accounts for its late distant recurrence.
• B. Pleomorphic adenoma is benign, the most common salivary tumour, showing epithelial and myoepithelial cells in a chondromyxoid stroma.
• C. Warthin tumour, or papillary cystadenoma lymphomatosum, has oncocytic bilayered epithelium over lymphoid stroma, occurs almost exclusively in the parotid, and is strongly linked to smoking.
• D. Mucoepidermoid carcinoma is a mix of mucous, epidermoid and intermediate cells and is the most common salivary malignancy overall, and the most common in children. It has no cribriform pattern.

Correct answer: C. Kaposi sarcoma

• A. An amalgam tattoo is a solitary blue-grey macule adjacent to a restored tooth or an extraction site, and metal fragments are sometimes visible radiographically.
• B. A pyogenic granuloma is a solitary red pedunculated mass that bleeds readily, arising from local irritation or hormonal change, not multiple flat palatal macules.
• C. Correct. Kaposi sarcoma is a vascular neoplasm driven by human herpesvirus 8. Intraorally it favours the hard palate and gingiva, starting as flat purple macules that coalesce and later become nodular and may ulcerate. It is an AIDS-defining illness.
• D. A haemangioma is usually a solitary developmental lesion present from early life that blanches on pressure. Multiple new palatal macules in advanced HIV do not fit.