Demographic and histological subtypes of Hurthle cell tumours of the thyroid in a South African setting

Abstract

Background: Report of Hurthle cells following fine needle aspiration cytology from a thyroid nodule raises possibility of Hurthle cell carcinoma (HCC), which is a distinct entity and accounts for 3–10% of thyroid malignancies.
Aim: To determine if there are demographic and histopathological features which may be used to differentiate HCC from Hurthle cell adenoma (HCA).
Methods: Histopathology records of patients who had thyroidectomy from January 2001 to October 2015 were reviewed. Data retrieved included indications for thyroidectomy, patients’ demographics, histology and preoperative FNAC results.
Results: At total of 2641 records were reviewed of which 25.6% (676/2641) were for neoplasms. 15.8% (107/676) of the neoplasms were Hurthle cell neoplasms (HCNs) and 25.2% (27/107) of HCNs were HCCs. 77.2% (71/92) of HCAs and 77.8% (21/27) of HCCs were from female patients. Preoperative FNAC results were available for 54.2% (58/107) and were suspicious of HCN in 12.1% (7/58). Average tumour size for HCCs and HCAs was 4.9 +/- 2.7 cm and 3.5 +/- 2.0 cm, respectively. The difference was statistically significant with a p-value of 0.016. The risk of malignancy increased from 11.1% in HCNs less than 1 cm to 53.8% for tumours which were greater than 4 cm in diameter.
Conclusion: HCNs are more common in females. The likelihood of HCC rises as the size of the HCN increases. Malignancy rate exceeds 50% for HCNs which are greater than 4 cm in diameter.

Key words: Hurthle cell neoplasm, Hurthle cell carcinoma, FNA, tumour size