SENSITIVITY OF INTRAOPERATIVE HISTOLOGICAL EXAMINATION IN THYROID CANCER

Aim. To study the diagnostic accuracy of urgent intraoperative histological examination during operations for thyroid cancer. Materials and Methods. The results of urgent intraoperative histological examination of 1531 patients operated for thyroid cancer in the period from 1992 to 2018 have been analyzed and have been compared with the results of planned histological examination in the same patients. An urgent morphological study was carried out by freezing a part of the tumor with carbon dioxide, tissue sections 15-20 microns thick being resected with a microtome. The obtained specimen has been stained with hematoxylin-eosin. Microscopic inspection has been carried out using an optical microscope with magnification x100. The planned histological examination was performed by fixing the specimen with 10% formalin, and placing it into paraffin. Sections up to 10 µm thick have been resected with a microtome and have been stained with hematoxylin-eosin. Microscopic inspection was performed with magnification x100. All urgent intraoperative histological studies were carried out by experienced morphologists (more than 30 years of experience). Results. Comparing the results of urgent and planned morphological examinations, 86 (5.6%) errors have been revealed. False positive errors occurred in 17 (1.1%) cases, false negative clinically insignificant errors were revealed in 40 (2.6%) cases. False-negative clinically significant errors were detected in 29 (1.9%) cases. In most cases (20 patients) there were difficulties in the differentiation of follicular adenoma and follicular thyroid cancer, in 3 cases it was difficult to differentiate between medullary cancer and follicular adenoma, and in 1 case an urgent examination diagnosed colloidal node with necrosis, while in the planned examination the diagnosis was papillary cancer. Conclusions. urgent intraoperative histological examination showed high diagnostic accuracy in verification of thyroid cancer (sensitivity 98.1%, clinically significant errors – 1.9%), the examination being carried out by an experienced morphologist. Follicular tumors and medullary thyroid cancer are considered to be the most difficult for differential diagnosis.