Cytomorphologic Features of a Polymorphous Low Grade Adenocarcinoma of the Palate

BACKGROUND: Polymorphous low grade adenocarcinoma (PLGA) is a histologically low grade tumor of minor salivary gland origin. It is important to differentiate PLGA from other salivary gland tumors with myoepithelial differentiation, such as pleomorphic adenoma, adenoid cystic carcinoma and epithelial myoepithelial carcinoma. Here we report 2 cases of PLGA originating in the palate and describe the cytomorphologic and immunocytochemical features. CASES: The patients were a 55-year-old woman and a 63-year-old man. Both presented with a mass in the palate. Clinically the mass appeared malignant, and resection was performed. Cytologically the tumor cells were composed of sheet clusters, pseudopapillary epithelial clusters, naked cells and stromal components. Immunocytochemically the tumor cells showed strong expression of carcinoembryonic antigen (CEA) and vimentin. CONCLUSION: PLGA may be difficult to distinguish from other salivary gland tumors with myoepithelial differentiation. However, the cytopathologist should be aware of the distinctive cytomorphologic features of PLGA, demonstrating immunopositivity to CEA and vimentin.