Cytomorphological Findings and Histological Correlation of Low-Grade Cribriform Cystadenocarcinoma of Salivary Gland in Fine-Needle Aspiration: A Case Study
A 57-year-old man had a barely palpable, nontender mass in the right cheek area, followed up over a nine-month period. Contrast-enhanced computed tomography revealed a mildly enhancing mass in an anterior superficial lobe of the right parotid gland (). On ultrasonography, the lesion appeared as an approximately 1.2 cm large, multiseptated, cystic, solid nodule (). FNA was performed and the cytologic examination led to a diagnosis of ductal epithelial proliferative lesion, favoring neoplasm, of uncertain malignant potential. Histologic confirmation was required.\nExcision of the lesion from the right parotid gland was performed. The surgical specimen revealed a tiny multicystic nodule (0.7 cm), which appeared to be surrounded by normal salivary gland tissue. The cut surface of the tumor was partly solid and partly cystic (). Microscopically, it was a salivary ductal epithelial neoplasm showing multiple cysts lined by relatively bland ductal cells and a partly solid proliferation of ductal cells (). Many of the superficial lining cells contained cytoplasmic apocrine-type microvacuoles that were periodic acid-Schiff-positive/diastase-resistant () and mucicarmine-positive (). The tumor cells were strongly and diffusely S-100 protein positive (). Myoepithelial markers (including actin and p63) highlighted the presence of cells surrounding the cystic spaces, confirming the intraductal nature of the lesion (). No invasive foci were noted. On the basis of these findings, we diagnosed the mass as a low grade cribriform cystadenocarcinoma, marginally excised.\nThe cellular smear showed many large sheets or clusters of ductal epithelial cells in an irregular overlapping arrangement (). These cytologic components could be aspirated from the solid area of this tumor (). Architecturally, the tumor cells had tight intercellular connections forming a vague cribriform (), solid, or pseudopapillary () arrangement. These were matched with histologic findings. The solid areas revealed a cribriform pattern, resembling ADH and low-grade ductal carcinoma in situ of the breast (). The pseudopapillary projections were found in the epithelial lining the cystic areas (). Cytologically, almost all tumor cells were bland looking, ductal epithelial cells with low nuclear/cytoplasmic (N/C) ratio. The nucleoli were found to be small, single, or entirely absent. Nuclear chromatin was fine or slightly coarse (). Squamoid or metaplastic changes of the tumor cells, mentioned by Nakazawa et al., were also identified in this case. Nuclear atypia was inconspicuous; however, one focus showed mild atypia with minimal nuclear size variation, prominent nucleoli, and vacuolated cytoplasm (, ). The background was relatively clear in the cystic space. Scattered inflammatory cells with hemosiderin-laden macrophages, neutrophils, and eosinophils were seen. No evidence of necrosis or mucin was found.\nWhole-body positron emission tomography-computed tomography scanning was conducted after surgery. A residual, enhancing nodular lesion in the anteriosuperior aspect of the right parotid gland showed mild, increased fluorodeoxyglucose uptake. Overall, residual malignancy was suggested. Postoperative chemotherapy or radiation therapy was not recommended. A follow-up was conducted two months later. At that time, the patient was healthy, with no evidence of recurrence or distant metastasis.