Thyroiditis is known to induce atypical cytomorphological changes in the thyroid accompanied by increased cancer risk. The current study aims to determine the effect of thyroiditis on the risk of neoplasm (RON), risk of malignancy (ROM), diagnostic concordance and clinico-radiological features associated with discordance in thyroid aspirates. A cohort of histology (thyroidectomy) matched thyroid aspirates were reviewed for medical history of thyroiditis, cytological and histological diagnosis, and clinico-radiological information. Cytology-histology concordance was determined in accordance with the Bethesda system 2023. There were 770 thyroid aspirates with lymphocytic thyroiditis (n = 106), Graves’ disease (n = 19), granulomatous thyroiditis (n = 3), IgG4-associated thyroiditis (n = 2), and non-specified autoimmune thyroiditis (n = 2). In the thyroiditis group, the RON/ROM in the Bethesda I to VI categories were 25.0%/21.4% (non-diagnostic/unsatisfactory), 31.3%/25.0% (benign), 45.2%/24.1% (atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS)), 33.3%/0% (follicular neoplasm/suspicious for follicular neoplasm), 100%/100% (suspicious for malignancy), and 100%/100% (malignant), respectively. In the non-thyroiditis group, the RON/ROM were respectively 51.5%/34.9%, 23.3%/8.9%, 44.8%/23.0%, 68.4%/21.1%, 94.8%/87.9%, and 100%/97.7%. The RON for non-diagnostic/unsatisfactory was higher in the non-thyroiditis group (p = 0.009). There were more AUS/FLUS aspirates in the thyroiditis group (47.0% vs. 37.5%, p = 0.042). With AUS/FLUS aspirates considered positive over negative, the concordance rate decreased (59.6% to 51.9%) in the thyroiditis group with a trended towards lower concordance than the non-thyroiditis group (51.9% vs. 61.4%, p = 0.074). Cases with lymphocytic thyroiditis showed a lower concordance rate (p = 0.010), and reciprocally Graves’ disease higher (p = 0.031). Other clinico-radiological parameters demonstrated no significant correlations. Decisions arising from AUS/FLUS aspirates in patients with thyroiditis may better err on the conservative side with assumptive negative diagnosis. In managing patients with lymphocytic thyroiditis, the lowered diagnostic accuracy of aspiration cytology should be taken into consideration. Not applicable.
Fung et al. (Wed,) studied this question.