Multifocality as an adverse histopathological factor in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is characterized by various clinical and pathomorphological features, such as metastases to the locoregional lymph nodes and radioiodine resistance. It could also be diagnosed as a microcarcinoma coexisting with other benign thyroid pathologies or as multifocal growth. Of these, multifocality in PTC is considered an unfavourable pathomorphological feature. However, the research findings are controversial. Objective — to investigate and evaluate the clinical and pathohistological features of multifocal PTC (mPTC) in comparison with unifocal (single nodule) PTC. Materials and methods. Among the patients who underwent operative treatment at the clinical bases of the Department of Surgery, Institute of Biology, and Medicine at Taras Shevchenko National University of Kyiv, 91 were diagnosed with PTC and were included in the study. Results. Out of the 91 patients, 31 (34%) had mPTC and 60 (66%) had PTC. Bilateral mPTC was diagnosed in 23 (74%) patients, which is in line with other studies. It is also worth mentioning, that 5 (16%) patients were diagnosed with multifocal growth only at the stage of histopathology section, without preoperative or intraoperative evidence of multifocality. A significantly higher frequency of locoregional metastasis was found in the mPTC group in 17 (55%) patients as compared to 18 (30%) patients with PTC (p=0.025). Lateral neck dissection was performed in 13 (42%) patients with mPTC, and in 13 (22%) patients with PTC (р=0.0525). Frozen section pathology was performed in 17 (24 patients with mPTC, and in 4 (10%) patients with PTC (р >0,05). Conclusions. A higher frequency of locoregional metastasis and a higher propensity for performing a lateral neck dissection are both indicators of a higher biological aggressiveness of the carcinoma in PTC multifocal growth.