Basement membrane-like substance in cytologic diagnosis in clear cell adenocarcinoma of the minor salivary gland of the palate. A case report

BACKGROUND: Clear cell adenocarcinoma (CCA) of the minor salivary gland accounts for < 1% of all tumors of the salivary gland. CASE: A 32-year-old woman with a history of papillary carcinoma of the thyroid 1 year earlier complained of pain on the left side of the neck. After a detailed examination, the patient underwent the resection of a tumor located at the palate. Imprint cytology of the tumor revealed cohesive tumor cells of uniform size containing an abundant clear cytoplasm and round nuclei with extra but fine granular chromatin and conspicuous nucleoli. A basement membrane-like substance (BMS) was stained in light green with Papanicolaou staining and was positive for laminin with immunohistochemical staining. Histopathologic analysis confirmed the trabecular or nest-like arrangement of the cells with the clear cytoplasm and BMS substance surrounded by tumor cells, which were positive for laminin and AE1 immunohistochemically. CONCLUSION: Although CCA of the palate is extremely rare, an accurate cytologic diagnosis can be made if the characteristic findings of CCA, including BMS, are imaged.