Malignancy of the lateral cysts of the neck: immunohistochemical diagnostic criteria

Objective. Identification of the main criteria for diagnosing malignancy of lateral neck cysts using immunohistochemical techniques. Material and methods. The article discusses four clinical cases of initially diagnosed lateral neck cysts. After the cystectomy operation, the biopsy material was examined in the In cased when malignancy was suspected after a standard histological examination, immunohistochemical examination with markers of proliferative activity (Ki-67) and cytokeratin (CK15) was performed using an Autosteiner 360 according to the Quanto protocol program using the PrimeBioMedTM .detection system. The expression of the Ki-67 marker was determined by the percentage of cells with stained nuclei to the total number of nuclei in 3 non-overlapping fields of view on an Axioplan 2 Imaging microscope at x400 magnification. Results. In the case of a benign process, proliferative activity of Ki-67 was noted in the basal layer of the epithelial lining, while no cell proliferation was observed in the overlying cellular layers. In the case of in situ carcinoma and squamous cell carcinoma, IHC examination revealed a high (50—60%) proliferative activity of Ki-67 cells, observed in all layers of the epithelial lining. Cytokeratin 15, which characterizes proliferating epithelial cells in the case of a benign process, was detected in the basal layer of the multilayer squamous epithelium. The expression of cytokeratin 15 in carcinoma in situ showed an uneven pattern in the tumor epithelial cells. In the examined cases of squamous cell carcinomas, the expression of this marker was characterized by a progressive diffuse signal in the tumor cells, depending on the increasing histological grade of the tumor. Conclusion. Thus, in order to exclude malignant transformation in the lateral cyst wall, the diagnostic algorithms should include an immunohistochemical study with markers on Ki-67 and CK15.