The prognostic importance of histological variants of well differentiated oncocytic tumors of thyroid

Objectives: To show whether the prognosis of oncocytic variant of papillary carcinoma (PCOV) differs from the oncocytic variant of follicular carcinoma (FCOV), and to evaluate the importance of histological features influencing tumor recurrence and prognosis Design: Retrospective study Setting: Department of Pathology, Faculty of Medicine, Ege University, Izmir, Turkey Subjects: Thirty cases diagnosed as oncocytic carcinomas of thyroid during the period of January 2000 to December 2011 were included in the study. Intervention: Demographical data, follow-up time, development of recurrence and/or distant metastasis, and macroscopical features of the tumors were evaluated. Hematoxylin-eosin stained slides of the cases were reviewed retrospectively. Main outcome measures: To show the prognostic difference of PCOV from FCOV and to evaluate the importance of histological features influencing tumor recurrence and prognosis Results: Twenty cases were PCOV and 10 were FCOV. Two of the FCOV and one PCOV case recurred locally. None of the cases of PCOV developed distant metastasis and all of these cases are alive. Only one FCOV case with extrathyroidal extension developed distant metastasis and two cases with extrathyroidal extension recurred locally. Four FCOV cases developed metastasis and three of these died from the disease. Vascular invasion was observed in most of the FCOV, but only in one of the PCOV cases. Significant association was found between the histological type of the tumor and survival, and also the vascular invasion. Conclusion: The diagnosis of oncocytic carcinomas, whether variants of papillary or follicular carcinomas, is essential, as the presence of vascular invasion and disease-free survival differs between the two variants. © 2018, Kuwait Medical Association. All rights reserved