Endocrine Abstracts

Introduction: The management of small size (≤ 1 cm) papillary thyroid carcinoma, also known as papillary thyroid microcarcinoma (PTMC) is a debated topic as it includes tumors with a wide range of biological characteristics and behavior.

Objectives: To describe prevalence, clinical and histological characteristics of PTMC with excellent response to treatment after a median follow up of 9.85±6.21 years.

Methods: We did a retrospective analysis of clinical and histopathological data of all patients operated on for thyroid cancer at our hospital between 1996 and 2013 with diagnosis of PTMC. Statistical analysis was done with SPSS 22.0 for MAC.

Results: During this period 1057 patients were diagnosed with PTMC. Of these 661 (577 females and 84 males with a mean age of 51.2±13.5 and 55.4±12.7 years, respectively) showed an excellent response to treatment. In 472 (72%) the diagnosis of PTMC was incidental and in 182 (27.8%) was non incidental. Incidental PTMC were significantly smaller than nonincidental (3.86±2.82 vs 7.43±2.36mm, P<.001). Initial surgery was lobectomy in 142 (21.5%), total thyroidectomy (TT) in 488 (73.8%), subtotal thyroidectomy in 5 (0.8%), totalization of thyroidectomy in 24 (3.6%) and TT+neck dissection in 2 (0.3%). Most cases were classical PTC and follicular variant of PTC (84% and 11%, respectively). In 547 (82.8%) cases no additional treatment was necessary after first surgery (group A), whereas in 114 (group B) another surgery and/or radioiodine was done. When comparing these groups we found significant differences between them in terms of age at diagnosis (71.7% were ≥45 years in group A vs 58.8% in B), incidental finding (77.8% in group A vs 45.6% in group B), multifocality (23.3% in group A vs 54.4% in B), vascular invasion (0.6% in group A vs 21.1% in B), extrathyroidal extension (2.8% in group A vs 26.3% in B), lymph node involvement (0% in group A vs 7.9% in B). During the follow-up tumor relapse occurred in 12 cases (1.8%), all locoregional, 8 initially treated with lobectomy and 4 with total thyroidectomy. The time to relapse was 5.08±5.56 (1-18) years.

Conclusion: PTMC is frequently found and the optimal treatment is still a matter of debate. Most of them had an excellent prognosis and no further treatment was needed after lobectomy or thyroidectomy. However some patients have clinical and histopathological poor prognostic factors as it is demonstrated in this series that justifies a longer follow-up.