Which of the following salivary gland tumors has the highest malignant potential and is most commonly associated with facial nerve paralysis?

Explanation

## Adenoid Cystic Carcinoma: The Most Aggressive Salivary Malignancy ### Clinical Characteristics **Key Point:** Adenoid cystic carcinoma (ACC) is the most aggressive salivary gland malignancy, characterized by perineural invasion and high recurrence rates. **High-Yield:** ACC accounts for ~10% of all salivary gland tumors but represents the most common malignancy of minor salivary glands. ### Pathological Features 1. **Perineural invasion** — hallmark finding; tumor cells invade along nerve sheaths 2. **Cribriform pattern** — characteristic "Swiss cheese" appearance on histology 3. **Slow growth** — deceptively indolent clinical course masks aggressive biology 4. **Facial nerve involvement** — perineural spread along CN VII causes facial paralysis in ~25% of cases ### Comparison with Other Salivary Malignancies | Feature | ACC | Mucoepidermoid Ca | Acinic Cell Ca | |---------|-----|-------------------|----------------| | **Perineural invasion** | Yes (hallmark) | Rare | Absent | | **Facial nerve palsy** | Common (25%) | Uncommon | Rare | | **5-year survival** | 40–50% | 70–80% | 90%+ | | **Recurrence rate** | High (40–60%) | Moderate | Low | | **Site preference** | Minor > major | Parotid > minor | Parotid | **Clinical Pearl:** A patient with a salivary gland tumor and facial nerve paralysis should raise suspicion for ACC until proven otherwise. ### Why ACC is Most Aggressive 1. **Perineural spread** — allows tumor to escape surgical margins and invade distant tissues 2. **Late presentation** — slow growth delays diagnosis; often presents at advanced stage 3. **High recurrence** — even after complete resection, recurrence occurs in 40–60% of cases 4. **Poor prognosis** — 5-year survival only 40–50%; worse than other salivary malignancies **Mnemonic:** ACC = **A**ggressive **C**ourse with **C**ranial nerve involvement (especially CN VII). ### Management Implications - Wide surgical excision with facial nerve sacrifice if involved - Adjuvant radiation therapy (even after complete resection) - Long-term follow-up essential due to high recurrence risk