Comparison of Clinical and Ultrasonographic Features of Poorly Differentiated Thyroid Carcinoma and Papillary Thyroid Carcinoma

Poorly differentiated thyroid carcinoma: molecular, clinico-pathological hallmarks and therapeutic perspectives

Poorly differentiated thyroid carcinoma (PDTC) is a rare and extremely aggressive tumor, accounting for about 2-15% of all thyroid cancer. PDTC has a distinct biological behavior compared to well-differentiated and anaplastic thyroid carcinoma and, in last years, it has been classified as a separate entity from both anatomopathological and clinical points of view. Nevertheless, there is still a lack of consensus among clinicians regarding inclusion criteria and definition of PDTC that affects its diagnosis and clinical management. Due to its rarity and difficulty in classification compared to other tumors, very few studies are available to date and series often include different histotypes in addition to PDTC. This review focuses on main studies concerning PDTC summarizing the evolution in the definition of its diagnosis criteria, clinicopathological features, management, and outcome. The data available confirm that the pathological evaluation and classification of PDTC are crucial and should therefore be standardized. Since the clinical presentation and prognosis of PDTC may vary widely depending on the different stage of the disease at diagnosis, the patient's management may differ in treatment and should be tailored to each patient. Finally, this review discusses advances in molecular insights of PDTC that, together with the implementation of both in vitro and in vivo models, will provide valuable insights into biological mechanisms of progression, metastasis, and invasion of this aggressive thyroid carcinoma. Further studies on larger, carefully selected series are needed to better assess the peculiar features of PDTC and to better define its management by focusing on the best diagnostic and therapeutic approaches.

Thyroid cancer necrosis not evident on imaging: A cautionary case series on poorly differentiated thyroid carcinoma diagnosed only on final pathology

OBJECTIVE

Poorly-differentiated thyroid cancer (PDTC) is a highly aggressive malignancy which is recently defined and understudied in the radiologic literature. Necrosis is a key histopathologic criterion for the diagnosis of PDTC. We illustrate the current difficulty in accurate identification of histopathologic necrosis on preoperative imaging.

METHODS

A series of seven patients with the final diagnosis of PDTC from our institution were identified. Multimodality preoperative imaging was analyzed by two head and neck radiologists. Final pathology reports were queried confirming histopathologic evidence of necrosis.

RESULTS

Patients presented with a wide range of preoperative imaging features. A consistent imaging appearance confirming necrosis was not identified. All patients were subsequently upstaged to PDTC following final pathological analysis.

CONCLUSION

A lack of definitive evidence of necrosis on preoperative imaging does not exclude the possibility of PDTC. We demonstrate the need for further research to establish a clear methodology for the preoperative diagnosis of PDTC.

Prognostic Impact of the Turin Criteria in Poorly Differentiated Thyroid Carcinoma

BACKGROUND

The Turin criteria including solid, trabecular, and/or insular architecture, lack of typical nuclear features of papillary carcinoma, and mitoses, necrosis, or convoluted nuclei were adopted in the recent 4th edition of the World Health Organization classification published in 2017.

MATERIALS AND METHODS

Between 2006 and 2017, 11,001 cases underwent initial surgery for primary malignant thyroid tumor derived from follicular cells. A total of 75 (0.7%) cases were diagnosed with PDTC according to the 2004 WHO classification. Based on the Turin criteria, 30 (40%) cases were re-classified as PDTC-Turin (+) and 45 (60%) cases were PDTC-Turin (-). Clinicopathological features and prognosis were compared between PDTC-Turin (+) and PDTC-Turin (-).

RESULTS

Seventy-five patients (48 females and 27 males) had a median age at the time of surgery of 57 years. Preoperative diagnosis was benign in 16 (21%), follicular tumor in 40 (53%), and malignant in 19 (25%). The 5-year cause-specific survival (CSS) and disease-free survival (DFS) rates were 97% and 44% for PDTC-Turin (+) and 100% and 88% for PDTC-Turin (-). On univariate analysis, CSS and DFS rates were significantly worse in the PDTC-Turin (+) than in the PDTC-Turin (-) (p = 0.0096, and p = 0.0016). Multivariate analysis showed that Turin criteria status, Ki-67 labeling index ≥ 10%, and age 55 ≥ years were the independent prognostic factors for recurrence.

CONCLUSIONS

The prevalence of PDTC diagnosed with the Turin criteria was low, but it showed more aggressive behavior. The 2017 WHO classification reflects the prognosis more accurately than the 2004 WHO classification.

Significance of clearing differentiated thyroid carcinoma lymph node by high-frequency color Doppler ultrasonography

We compared the clinical effects and prognosis of patients receiving lymph node dissection after surgical removal of the thyroid tissues and those not receiving it after the removal. A total of 80 patients diagnosed with differentiated thyroid carcinoma (DTC) by our hospital from March 2012 to March 2014 were successively included in the study. The cases were divided into the control group (n=36 cases) and observation group (n=44 cases), and the two groups underwent total or subtotal resection of the thyroid. In the control group, patients underwent preoperative high-frequency color ultrasonography, and the most suspicious lymph node was removed. In the observation group, patients underwent preoperative high-frequency color ultrasonography, and the surgeons cleared the lymph node of the widest range. Difference in clinical effects and prognosis of the two groups were compared. After nearly a year's follow-up observation, the tumor recurrence rate of the observation group was significantly lower than that of the control group and the survival rate of the observation group was significantly higher than that of the control group (P<0.05). The rate of surgery complications and comparative difference of the two patient groups had no statistical significance (P>0.05). When comparing the data of lymphatic metastasis tested by preoperative high-frequency color ultrasonography with intraoperative diagnosed figures, sensitivity was 97.4%, specificity 33.3%, positive predictive value 90.2% and the negative predictive value 66.7%. In conclusion, removal of the lymph node for DTC patients having undergone thyroid tissue excision with preoperative high-frequency color ultrasonography can be beneficial to improve the effects along with reduction in the recurrence rate.