Impact of tall cell variant histology on predicting relapse and changing the management of papillary thyroid carcinoma patients.

ABSTRACT

OBJECTIVE: There has been much discussion recently about the risk category of tall cell variant (TVC) histology and its effects on the management of papillary thyroid carcinoma (PTC). We, therefore, undertook a retrospective study to compare stage-matched risk factors and recurrence rates between classical PTC (cPTC) patients and patients with TCV histology. SUBJECTS AND METHODS: A total of 3128 well-differentiated thyroid carcinoma patients who were treated and followed-up for more than 5 years in our clinic from 1995 to 2016 were included in this study. There were 2783 PTC (89%) patients, 1113 (40%) of them were cPTC and 56 (2%) of them were TCV patients. RESULTS: In all stages, the stage-matched incidence of extrathyroidal extension (ETE), lymphovascular invasion and initial lymph node metastases were significantly higher in TCV patients than in cPTC patients (P<0.001). Recurrence was in 10 of 27 patients (37%) with TCV and in 91 of 890 (10%) patients with cPTC diagnosed in stage I (odds ratio (OR)=5.16); in 4 of 6 patients with TCV and 18 of 84 (21%) patients with cPTC in stage II (OR=7.33); in 5 of 6 patients with TCV and 11 of 46 (23%) patients with cPTC in stage III (OR=15.90); and in 13 of 17 patients with TCV and 31 of 93 (33%) patients with cPTC in stage IV (OR=6.50). Stage-matched recurrence rates were found significantly higher in all stages of TCV patients than in cPTC patients (OR=8.49, P<0.001). Recurrence with distant metastases was seen more frequently in TCV patients than in cPTC patients (P<0.001) and treatment of metastatic disease was more difficult in TCV patients. CONCLUSION: Tall cell variant was an independent poor prognostic factor in papillary thyroid carcinoma patients even if they were diagnosed at early stages of the disease. Patients with tall cell variant histology required more aggressive therapeutic approach and closer follow-up than classical patients.