Abstract and Introduction
Abstract
Context: Tumor size is important in determining the range of surgery in papillary thyroid carcinomas (PTCs), especially those smaller than 1 cm.
Objective: We aimed to analyze the features of small PTCs with aggressive subtypes based on histological characteristics.
Methods: In this retrospective study, we reviewed the medical records of 11 570 patients with PTCs smaller than or equal to 1 cm who underwent thyroidectomy between January 2009 and December 2016. Aggressive subtypes included diffuse sclerosing, solid, tall cell, columnar cell, and hobnail subtypes.
Results: Among the 11 570 patients with PTCs smaller than or equal to 1 cm, 177 aggressive PTC subtypes were identified. Propensity score matching revealed 110 tumors (62.1%) with extrathyroidal extension of aggressive PTC subtypes and 451 (51.1%) nonaggressive PTC subtypes (95% CI, 0.41–0.80; P < .001). Metastatic central and lateral neck lymph nodes constituted 3.06 ± 3.67 and 3.81 ± 5.39 of aggressive PTC subtypes and 1.22 ± 2.14 and 2.85 ± 3.79 of nonaggressive PTC subtypes, respectively (central neck nodes: 95% CI, 1.42–2.26; P < .001; lateral neck nodes: 95% CI, 2.9–5.90; P < .001). Seven patients with aggressive PTC subtypes (3.95%) and 12 with nonaggressive PTC subtypes (1.7%) exhibited recurrence.
Conclusion: Aggressive subtypes of small PTC tumors smaller than or equal to 1 cm exhibited more extrathyroidal extension and neck node metastasis. This study suggests that surgeons should consider the aggressive subtypes as important factors when deciding the range of surgery in PTCs smaller than 1 cm.
Introduction
Papillary thyroid carcinoma (PTC) is the most common histological type of differentiated cancer of the thyroid gland.[1] PTC is an indolent tumor with a 10-year survival rate of approximately 93%.[2] Papillary thyroid microcarcinoma (PTMC), which is defined as PTC with a size of 1 cm or less in the greatest diameter, is associated with differences in prognosis and treatment. However, PTMC was not included as a PTC subtype in the 2022 World Health Organization classification of thyroid neoplasms.[3] Small PTCs sized 1 cm or less constitute approximately 50% of the increase in PTC incidence.[4] However, some aggressive PTC subtypes exhibit distinct clinical, pathological, and molecular features associated with their large size.[5] Generally, diffuse sclerosing, solid, tall cell, columnar cell, and hobnail subtypes are considered traditional aggressive subtypes.[4]
These aggressive subtypes possess distinct features associated with their large size and present with extrathyroid extension and nodal metastases. The diffuse sclerosing subtype exhibits unique clinical features, including a higher prevalence of underlying Hashimoto thyroiditis, higher female-to-male ratio, younger age, high vascular invasion, extrathyroid extension, and lymph node metastasis.[6,7] The tall cell subtype occurs in older patients and presents with larger tumor size and more frequent extrathyroidal involvement.[8] The columnar cell subtype exhibits a rapid growth rate, local invasion, early development of lymph node metastasis, extrathyroidal extension, and high recurrence rate.[9]
PTC subtypes with small tumor sizes (≤ 1 cm) may exhibit aggressiveness, but there is a paucity of studies in this regard, thus preventing optimal decision-making in treating small PTCs with aggressive subtypes.[10] Thus, our study aimed to analyze the features of small PTCs with aggressive subtypes based on histological characteristics.
J Clin Endocrinol Metab. 2023;108(6):1370-1375. © 2023 Endocrine Society
