Clinicopathological Characteristics and Disease-Free Survival in Patients with Hürthle Cell Carcinoma: A Multicenter Cohort Study in South Korea

Molecular Alterations and Comprehensive Clinical Management of Oncocytic Thyroid Carcinoma: A Review and Multidisciplinary 2023 Update

Importance

Oncocytic (Hürthle cell) thyroid carcinoma is a follicular cell-derived neoplasm that accounts for approximately 5% of all thyroid cancers. Until recently, it was categorized as a follicular thyroid carcinoma, and its management was standardized with that of other differentiated thyroid carcinomas. In 2022, given an improved understanding of the unique molecular profile and clinical behavior of oncocytic thyroid carcinoma, the World Health Organization reclassified oncocytic thyroid carcinoma as distinct from follicular thyroid carcinoma. The International Thyroid Oncology Group and the American Head and Neck Society then collaborated to review the existing evidence on oncocytic thyroid carcinoma, from diagnosis through clinical management and follow-up surveillance.

Observations

Given that oncocytic thyroid carcinoma was previously classified as a subtype of follicular thyroid carcinoma, it was clinically studied in that context. However, due to its low prevalence and previous classification schema, there are few studies that have specifically evaluated oncocytic thyroid carcinoma. Recent data indicate that oncocytic thyroid carcinoma is a distinct class of malignant thyroid tumor with a group of distinct genetic alterations and clinicopathologic features. Oncocytic thyroid carcinoma displays higher rates of somatic gene variants and genomic chromosomal loss of heterozygosity than do other thyroid cancers, and it harbors unique mitochondrial DNA variations. Clinically, oncocytic thyroid carcinoma is more likely to have locoregional (lymph node) metastases than is follicular thyroid carcinoma-with which it was formerly classified-and it develops distant metastases more frequently than papillary thyroid carcinoma. In addition, oncocytic thyroid carcinoma rarely absorbs radioiodine.

Conclusions and Relevance

The findings of this review suggest that the distinct clinical presentation of oncocytic thyroid carcinoma, including its metastatic behavior and its reduced avidity to radioiodine therapy, warrants a tailored disease management approach. The reclassification of oncocytic thyroid carcinoma by the World Health Organization is an important milestone toward developing a specific and comprehensive clinical management for oncocytic thyroid carcinoma that considers its distinct characteristics.

Oncocytic carcinoma of the thyroid: Conclusions from a 20-year patient cohort

BACKGROUND

Oncocytic carcinoma (OCA) was recently reclassified as a distinct differentiated thyroid carcinoma (DTC). Given its rarity, OCA studies are limited. This study describes the characteristics of OCA in a 20-year cohort.

METHODS

Retrospective analysis of patients with OCA at a single tertiary care hospital from 2000 to 2021.

RESULTS

Fifty-one OCA patients (22M:29F) were identified. The mean age at diagnosis was 60.3 years; 90% presented as palpable mass; 24% had a family history of thyroid cancer. None had vocal fold paresis. On ultrasound, most tumors were solid and hypoechoic. FNA (n = 14) showed Bethesda-4 lesions in 93%. All were treated surgically. Histologically, 63% demonstrated angioinvasion, 35% had lymphovascular invasion, and 15% had extrathyroidal extension. Radioactive iodine was used as adjunct therapy in 77%.

CONCLUSION

OCA has distinct features that distinguish it from other DTCs, and additional focused studies will help clarify the aggressive nature, treatment options, and prognosis of the disease.

Hürthle Cell Carcinoma: Single Center Analysis and Considerations for Surgical Management Based on the Recent Literature

BACKGROUND

Hürthle cell carcinoma (HCC) of the thyroid is rare. There are contrasting data on its clinical behavior. The aim of this study was to describe clinic-pathological features and outcomes of HCC patients at our institution, in order to adapt our surgical management.

METHODS

We retrospectively studied 51 cases of HCC treated at the interdisciplinary endocrine center of the University Hospital of Cologne, Germany between 2005 and 2020.

RESULTS

Patients median age was 63 years (range 29-78) with 64.7% of cases being female. Primary treatment included surgery and postoperative radioiodine therapy with 3.7 GBq in all patients. Surgery consisted of total thyroidectomy in all cases and additional central lymphadenectomy in 90.2% of cases. The median number of harvested lymph nodes was 11 (range 2-31). Lymph node involvement was found in two (4.3%) pT4a tumors. In all other cases (95.7%), central lymphadenectomy was prophylactic and lymph nodes were free of metastasis in final histopathology. Twelve (23.5%) patients with incomplete biochemical response to primary treatment were diagnosed with structural relapse during the course of disease, for which seven (58.4%) underwent resection of isolated cervical metastasis. Histopathology revealed soft tissue implants in all cases and cervical surgery led to biochemical and radiologic cure in only two (28.5%) cases. Five (41.6%) patients developed metastatic disease, followed by systemic therapy in two patients. Vascular invasion of the primary tumor was significantly associated with relapse (p<0.01).

CONCLUSIONS

Recurrence of HCC was common in this study. Given the low rate of lymph node metastases both in this study and in recent literature and the nature of relapse (soft tissue instead of nodal metastasis), the benefit of routine prophylactic central lymph node dissection for HCC remains unclear, especially in the absence of vascular invasion from the primary tumor.