Adenoid cystic carcinoma of the parotid gland is known for perineural invasion. Which of the following best describes its behaviour and the clinical consequence of perineural invasion?
- A It metastasizes rapidly to regional lymph nodes but rarely causes cranial nerve deficits
- B Perineural invasion causes facial nerve palsy and allows skip lesion spread along nerve sheaths to the skull base and intracranially; late haematogenous metastasis to lungs is characteristic ✓
- C Local recurrence is the main concern; perineural invasion does not affect prognosis
- D It is a low-grade tumour with 5-year cure rates >90% following excision alone
Explanation
Adenoid cystic carcinoma (ACC) is notorious for perineural invasion — malignant cells track along nerve sheaths, causing pain, paraesthesia, and progressive facial nerve palsy. This spread may skip apparent clear margins and travel along the facial nerve into the temporal bone or along other cranial nerves to the skull base, making true local control extremely difficult. Haematogenous spread (particularly to lungs) occurs late and paradoxically after decades, yet pulmonary metastases can be slow-growing. Regional lymph node metastasis is less common than in mucoepidermoid carcinoma. Prognosis with long-term follow-up (>10–15 years) is poor despite initial apparent control.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.