Comparison of unexpected vs preoperatively diagnosed thyroid carcinomas

Aim of study is to determine main diagnostic, management and outcome differences in thyroid cancer which were unexpected findings and those diagnosed prior operations. From 2015-2020 were performed 1475 thyroid operations. Thyroid cancer was diagnosed in 456 (30.9%) patients. From those unexpected cancers diagnosed in 110 (24.1%) patients – Group A, 346 (75.9%) were preoperatively diagnosed carcinomas – Group B. Data were analysed regarding indications for surgery, operation type, morphology, tumour size, thyroid weight. Main indications for surgery in Group A were compression symptoms –71 and thyrotoxicosis – 39 vs in Group B – suspected malignancy in 144, a proven malignancy – 196 cases. Fine needle aspiration (FNA) was performed in Group A in 57 (51.8%), B - 333 (96.2%) cases. Thyroidectomy performed in Group A: 65 (59.1%), B –297 (85.8%); unilateral procedure: Group A – 37 (33.6%), B – 46 (13.3%). Papillary cancers found in Group A – 83 (75.5%), B – 312 (90.2%); follicular cancers – Group A: 21 (19.1%), B - 20 (5.8%). Medullary cancer and anaplastic cancer found in Group A and B respectively: 2 (1.8%) and 2 (1.8%) vs 11 (3.2%) and 0 (0 %). Multiple different cancers Group A: 2 (1.8%), B - 3 (0.9%). Microcarcinomas found in Group A – 77 (70.0%), B – 162 (46.8%). Mean tumour size in Group A: 13.4mm (1–95 mm), B – 14.0mm (1–75mm). Multifocal cancers found in Group A: 21 (19.1%), B – 86 24.9%. Mean excised thyroid weight in Group A – 53.9g, B – 30.0g. Metastatic lymph nodes were diagnosed in 8 (7.2%) cases in Group A, B – 80 (23.1%). Unexpected thyroid cancer is not rare finding in patients operated due to benign pathologies. Large part of follicular cancers is still found incidentally despite commonly performed FNA.