Differentiated high-grade thyroid carcinoma (DHGTC): clinicopathological analysis of a new entity in a chilean center
摘要
High-grade differentiated thyroid carcinoma (DHGTC) is a rare cancer with an intermediate behavior between well-differentiated thyroid carcinoma (WDTC) and anaplastic thyroid carcinoma. In 2022, the WHO defined DHGTC by the presence of ≥ 5 mitoses per 2 mm² and/or tumor necrosis in tumors that retain the morphological and immunohistochemical features of carcinomas derived from follicular thyroid cells.
ObjectivesTo report the clinicopathological characteristics and outcomes of patients with DHGTC treated at a national center.
DesignRetrospective observational study.
MethodsThirty-two patients with a confirmed diagnosis of DHGTC were included. The extent of surgery was defined according to thyroid fine-needle aspiration (FNA) and preoperative imaging, and the need for additional therapies based on histology, imaging, and postoperative thyroglobulin (Tg). Clinicopathological variables and follow-up every 6 months with neck ultrasound, Tg, and anti-Tg antibodies (TgAb) were recorded.
ResultsOf the 32 patients, 27 (84.4%) were women, with a mean age of 39.8 ± 15.6 years and a median tumor size of 2.0 cm (range 0.5-6.0). Ultrasound was ACR-TIRADS 3, 4, and 5 in 3 (9%), 8 (26%), and 20 (65%) patients, and FNA resulted in Bethesda III-IV and V-VI in 8 (26%) and 23 (74%) cases, respectively. Eleven (34.4%) patients were treated with total thyroidectomy (TT), 11 (34.4%) with TT and lymph node dissection, and 10 (31.3%) with lobectomy (of these, 5 (50%) underwent completion thyroidectomy after histology was known). Twenty-seven (84.4%) had papillary thyroid carcinoma (PTC) and 5 (15.6%) follicular thyroid carcinomas (FTC). Among PTCs, 10 (37%), 5 (18.5%), 4 (14.8%), 3 (11.2%), and 5 (18.5%) were tall cell (TC), solid, classic, follicular, and other subtypes, respectively. Twenty-three (72%) had only ≥ 5 mitoses, 6 (18.6%) had only necrosis, and 3 (9.4%) had both (median mitosis count 6.5; range 5–11). In univariate analysis, male sex, age, and tumor diameter were associated with distant metastasis. Radioiodine was indicated in twenty-seven (84.4%) patients, of which 25 (77.7%) received a median dose of 50 mCi (range 30–200). According to AJCC 8, 28 (87.6%), 2 (6.2%), and 2 (6.2%) were stage I, II, and IVb, respectively. Thirty (93.7%) were followed for more than one year (median 2.3 years, range 1.91–6.92 years). At the end of the follow-up, all were alive, 19 (63.4%) had an excellent response, 6 (20%) had an indeterminate biochemical response, 3 (10%) had an incomplete biochemical response, and 2 (6.6%) had an incomplete structural response due to pulmonary metastases.
ConclusionsDHGTC is rare, but its frequency will likely increase following the WHO publication. In our series, most cases correspond to PTC, with a high frequency of aggressive subtypes. After a median follow-up of 2.3 years, there were no deaths, and two patients had an incomplete structural response. Larger studies and longer follow-ups are needed to understand this disease’s behavior and personalize its management.