Objective: The 2022 WHO classification introduced differentiated high-grade thyroid carcinoma (DHGTC) as a distinct category characterized by high-grade features despite maintained differentiation. Therefore, this study aims to evaluate its clinical characteristics, treatment responses, and the prognostic impact of the Ki-67 proliferation index in this patient population. Methods: We retrospectively reviewed 3100 patients with differentiated thyroid carcinoma (DTC) between 2017 and 2024. From this baseline pool, a total of 56 patients (1.8%) were identified and re-classified as DHGTC based on mitotic count (≥5/2 mm²) and/or tumor necrosis. Additionally, 69 DTC patients (2.2%) with an elevated Ki-67 index (>5%) identified from the same baseline pool—representing an overlapping group with the DHGTC cohort—were analyzed to evaluate its clinical significance. Results: In the DHGTC group, tumor necrosis was present in 87.5% and high mitotic activity in 19.6% of cases. While all DHGTC patients were classified as high-risk under 2025 American Thyroid Association (ATA) guidelines, 42.8% showed biochemical or structural incomplete response at the last follow-up and 28.6% required additional salvage interventions. In the broader DTC cohort, Ki-67 ≥ 15% was significantly associated with older age, larger tumor size, extensive invasion, and poorer treatment response (p < 0.05). However, within the DHGTC subset, Ki-67 ≥ 15% was only significantly associated with increased lymphovascular invasion and more extensive surgery. Conclusions: DHGTC carries a significant burden of aggressive histopathological features and a high risk of structural disease persistence or recurrence. While an elevated Ki-67 index (≥15%) serves as an adverse marker in general DTC, its additional prognostic value within the high-grade DHGTC cohort remains inconclusive, potentially obscured by limited statistical power due to small subgroup sizes.

Background/Objectives: The aim of this retrospective study was to characterize the preoperative hormonal, biochemical, and imaging features of adrenal lesions (ALs) and to assess differences in these features between benign and malignant lesions. Methods: This was a retrospective, single-center observational study conducted at the Endocrinology Clinic of Ankara Bilkent City Hospital. We reviewed the medical records of all patients referred to our clinic for the evaluation of an AL between February 2019 and August 2025. Demographic and clinical data and initial imaging were extracted from electronic medical records. Results: A total of 157 patients who underwent adrenalectomy were included in the analysis. Of these, 98 patients were female (62.4%) and 59 were male (37.6%). The mean age of the patients was 51.2 ± 12.54 years. Functionally, the findings were pheochromocytoma (n:44), overt Cushing syndrome (n:17), mild autosomal cortisol secretion (n:29), primary hyperaldosteronism (n:18), and non-functional (n:47). One patient had pheochromocytoma and mild autosomal cortisol secretion, and one patient had overt Cushing syndrome and primary hyperaldosteronism. Of the adrenal lesions, 70 (44.6%) were on the right, 71 (45.2%) on the left, and 16 (10.2%) were bilateral. 9% (7/79) of lesions measuring 4 cm and above, and 14% (4/28) of lesions measuring 6 cm and above were found to be malignant. The malignancy rate was 22% (4/18) in lesions located on the right and measuring 6 cm and above. All adrenocortical carcinomas were larger than 4 cm (8.3 ± 3.46) and all were on the right. The highest-grade malignant epithelial tumor was 12.9 cm and on the right. The malignant pheochromocytoma was 5.2 cm and on the left. It was determined that the frequency of right adrenal localization was significantly higher in the malignant group (85.7%) compared to the benign group (42.7%) (p = 0.045). Right tumor diameter (p = 0.002) and right and/or left tumor diameter (p < 0.001) were significantly higher in malignant lesions compared to benign lesions. Logistic regression analysis also supported a significant relationship between tumor size and malignancy. Conclusions: In our study, 9% (7/79) of lesions measuring 4 cm and above, and 14% (4/28) of lesions measuring 6 cm and above were found to be malignant. The malignancy rate in lesions on the right side measuring 6 cm and above was determined to be 22% (4/18). Although benign masses constituted the majority of lesions measuring 4 cm and above, all adrenocortical carcinomas were above 4 cm (8.3 ± 3.46). In light of the current findings, tumor size was observed to be associated with the distinction between malignant and benign adrenal lesions and may be considered an important descriptive characteristic in the clinical assessment of adrenal lesions.

Background/Objectives: Fine-needle aspiration biopsy (FNAB) is the primary diagnostic procedure for the evaluation of thyroid nodules. Although considered safe and minimally invasive, its immediate systemic biochemical effects, particularly those related to oxidative stress and mechanical tissue injury, remain insufficiently characterized. This study aimed to evaluate the acute systemic impact of FNAB on oxidative stress parameters and to determine whether these changes correlate with cytological malignancy risk. Methods: A total of 208 patients undergoing ultrasound-guided FNAB for a solitary thyroid nodule were prospectively included. Venous blood samples were collected in the supine position immediately before and within 1 min after the procedure. Thiol–disulfide homeostasis parameters were measured using an automated spectrophotometric method, and ischemia-modified albumin (IMA) levels were analyzed concurrently. Pre- and post-procedural values were compared using the Wilcoxon signed-rank test. Associations between oxidative stress markers and Bethesda cytological categories were assessed using Spearman’s correlation analysis. Results: Native thiol and IMA levels demonstrated statistically significant changes following FNAB, whereas total thiol, disulfide levels, and derived thiol–disulfide ratios remained unchanged. The reduction in IMA levels was predominantly observed in lower-risk cytological categories. No significant correlations were identified between oxidative stress parameters and Bethesda-based malignancy risk. Conclusions: FNAB induces only minor and transient alterations in selected systemic oxidative stress markers, which are clinically inconsequential. The observed changes in native thiol and IMA levels appear to reflect short-term procedural effects rather than malignancy-associated redox alterations. These findings support the systemic safety of FNAB and emphasize the need for careful temporal standardization when interpreting circulating oxidative biomarkers in thyroid nodule research.