[Cytologic diagnosis of adenoid cystic carcinoma of salivary glands and distinction from basal cell adenoma].

To describe the cytologic features of adenoid cystic carcinoma (ADCC) of salivary glands, and to identify distinguishing cytologic features of ADCC and basal cell adenoma (BCA). A retrospective review of cytology smears of 30 cases of ADCC and 12 cases of BCA of salivary glands were performed. All cases were collected from Beijing Tongren Hospital, Capital Medical University from January 2010 to January 2017. Except for 2 aspirate smears of ADCC, all were touch imprint smears. All cases had further histological confirmation. Neoplastic ductal cells of ADCC were arranged in three-dimensional clusters, sheets and singles. Hyaline globules were found in most cases (20/30, 66.7%). The nuclei were round to oval, showing varying degrees of nuclear atypia. These included (1) the nuclei were hyperchromatic, demonstrating coarse or slightly coarse, irregularly distributed chromatin; (2) the nuclei were slightly large and vary in size; (3) appearance of the nuclei had a different degree of irregularity (often mild). Nucleoli were common seen (21/30, 70.0%), and were prominent in some cases. Mitosis and necrosis were rare. Cytologically, BCA showed cell arrangements and nuclear features overlapped with those of ADCC. The cytologic difference between these two tumors included: (1) the tumor cells presented rarely in singles; (2) hyaline globules were very uncommon (1/12) in BCA; (3) nuclei of BCA were hypochromatic or slightly hyperchromatic, homogeneous and uniform in appearance and size, overall without nuclear atypia and they were smaller and slender then those of ADCC and (4) individual cells of BCA showed relatively abundant cytoplasm. The cytologic features of ADCC and BCA both overlap and different from each other. Most cases can be diagnosed by cytologic examination. The presence of hyaline globules is an important diagnostic clue of ADCC, although not pathognomonic. Nuclear atypia of neoplastic ductal cells is an essential cytological feature in the diagnosis of ADCC, and is the most reliable point for differential diagnosis of ADCC and BCA.