A 50-year-old male presents with a painless, slow-growing parotid swelling. FNAC reveals 'basaloid cells in a cylindromatous pattern with mucoid stromal deposits.' CT shows the mass involves deep lobe with perineural spread along the facial nerve. The most likely diagnosis is:
- A Adenoid cystic carcinoma ✓
- B Pleomorphic adenoma
- C Mucoepidermoid carcinoma (high grade)
- D Acinic cell carcinoma
Explanation
Adenoid cystic carcinoma (ACC) is characterized histologically by a cribriform/cylindromatous pattern with islands of basaloid cells surrounding cylindrical hyaline stromal deposits (mucoid matrix), creating a 'Swiss cheese' appearance. Its defining clinical feature is perineural invasion and spread — it tracks along nerve sheaths over long distances, explaining the facial nerve involvement seen here. Despite slow growth, it has a poor long-term prognosis due to perineural spread, distant metastases (commonly to lungs), and high recurrence rate. Mucoepidermoid carcinoma would show mucous, epidermoid, and intermediate cells on FNAC.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.