The fifth edition of the World Health Organization (WHO) histologic classification of thyroid neoplasms released in 2022 includes newly recognized tumor types, subtypes, and a grading system. Follicular cell-derived neoplasms are categorized into three families (classes): benign tumors, low-risk neoplasms, and malignant neoplasms. The terms “follicular nodular disease” and “differentiated high-grade thyroid carcinoma” are introduced to account for multifocal hyperplastic/neoplastic lesions and differentiated thyroid carcinomas with high-grade features, respectively. The term “Hürthle cells” is replaced with “oncocytic cells.” Invasive encapsulated follicular and cribriform morular variants of papillary thyroid carcinoma (PTC) are now redefined as distinct tumor types, given their different genetic alterations and clinicopathologic characteristics from other PTC subtypes. The term “variant” to describe a subclass of tumor has been replaced with the term “subtype.” Instead, the term “variant” is reserved to describe genetic alterations. A histologic grading system based on the mitotic count, necrosis, and/or the Ki67 index is used to identify high-grade follicular-cell derived carcinomas and medullary thyroid carcinomas. The 2022 WHO classification introduces the following new categories: “salivary gland-type carcinomas of the thyroid” and “thyroid tumors of uncertain histogenesis.” This review summarizes the major changes in the 2022 WHO classification and their clinical relevance.

Over the past years, pituitary hormones and their receptors have been shown to have non-traditional actions that allow them to bypass the hypothalamus-pituitary-effector glands axis. Bone cells―osteoblasts and osteoclasts―express receptors for growth hormone, follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), prolactin, oxytocin, and vasopressin. Independent skeletal actions of pituitary hormones on bone have been studied using genetically modified mice with haploinsufficiency and by activating or inactivating the receptors pharmacologically, without altering systemic effector hormone levels. On another front, the discovery of a TSH variant (TSH-βv) in immune cells in the bone marrow and skeletal action of FSHβ through tumor necrosis factor α provides new insights underscoring the integrated physiology of bone-immune-endocrine axis. Here we discuss the interaction of each pituitary hormone with bone and the potential it holds in understanding bone physiology and as a therapeutic target.

Paget's disease of the bone is a prevalent bone disease characterized by disorganized bone remodeling; however, it is comparatively uncommon in East Asian countries, including China, Japan, and Korea. The exact cause still remains unknown. In genetically susceptible individuals, environmental triggers such as paramyxoviral infections are likely to cause the disease. Increased osteoclast activity results in increased bone resorption, which attracts osteoblasts and generates new bone matrix. Fast bone resorption and formation lead to the development of disorganized bone tissue. Increasing serum alkaline phosphatase or unique radiographic lesions may serve as the diagnostic indicators. Common symptoms include bone pain, bowing of the long bones, an enlarged skull, and hearing loss. The diagnosis is frequently confirmed by radiographic and nuclear scintigraphy of the bone. Further, bisphosphonates such as zoledronic acid and pamidronate are effective for its treatment. Moreover, biochemical monitoring is superior to the symptoms as a recurrence indicator. This article discusses the updates of Paget's disease of bone with a clinical case.

Parathyroidectomy is the treatment of choice for primary hyperparathyroidism when the clinical criteria are met. Although bilateral neck exploration is traditionally the standard method for surgery, minimally invasive parathyroidectomy (MIP), or focused parathyroidectomy, has been widely accepted with comparable curative outcomes. For successful MIP, accurate preoperative localization of parathyroid lesions is essential. However, no consensus exists on the optimal approach for localization. Currently, ultrasonography and technetium-99m-sestamibi-single photon emission computed tomography/computed tomography are widely accepted in most cases. However, exact localization cannot always be achieved, especially in cases with multiglandular disease, ectopic glands, recurrent disease, and normocalcemic primary hyperparathyroidism. Therefore, new modalities for preoperative localization have been developed and evaluated. Positron emission tomography/computed tomography and parathyroid venous sampling have demonstrated improvements in sensitivity and accuracy. Both anatomical and functional information can be obtained by combining these methods. As each approach has its advantages and disadvantages, the localization study should be deliberately chosen based on each patient's clinical profile, costs, radiation exposure, and the availability of experienced experts. In this review, we summarize various methods for the localization of hyperfunctioning parathyroid tissues in primary hyperparathyroidism.

Background: This study aimed to investigate the long-term effects of diabetes drug costs on cardiovascular (CV) events and death.
Methods: This retrospective observational study used data from 2009 to 2018 from the National Health Insurance in Korea. Among the patients with type 2 diabetes, those taking antidiabetic drugs and who did not have CV events until 2009 were included. Patients were divided into quartiles (Q1 [lowest]-4 [highest]) according to the 2009 diabetes drug cost. In addition, the 10-year incidences of CV events (non-fatal myocardial infarction, stroke, hospitalization for heart failure, and coronary revascularization) and CV death (death due to CV events) were analyzed.
Results: A total of 441,914 participants were enrolled (median age, 60 years; men, 57%). CV events and death occurred in 28.1% and 8.36% of the patients, respectively. The 10-year incidences of CV events and deaths increased from Q1 to 4. After adjusting for sex, age, income, type of diabetes drugs, comorbidities, and smoking and drinking status, the risk of CV events significantly increased according to the sequential order of the cost quartiles. In contrast, the risk of CV death showed a U-shaped pattern, which was the lowest in Q3 (hazard ratio [HR], 0.953; 95% confidence interval [CI], 0.913 to 0.995) and the highest in Q4 (HR, 1.266; 95% CI, 1.213 to 1.321).
Conclusion: Diabetes drug expenditure affects 10-year CV events and mortality. Therefore, affording an appropriate diabetes drug cost at a similar risk of CV is an independent protective factor against CV death.

Background: The present study investigates whether modifiable behavioral factors of current cigarette smoking, heavy alcohol consumption, and regular exercise are associated with risk of lower extremity amputation (LEA) in diabetic patients.
Methods: A total of 2,644,440 diabetic patients (aged ≥20 years) was analyzed using the database of the Korean National Health Insurance Service. Cox proportional hazard regression was used to assess adjusted hazard ratios (HRs) for the behavioral factors with risk of LEA under adjustment for potential confounders.
Results: The risk of LEA was significantly increased by current cigarette smoking and heavy alcohol consumption (HR, 1.436; 95% confidence interval [CI], 1.367 to 1.508 and HR, 1.082; 95% CI, 1.011 to 1.158) but significantly decreased with regular exercise (HR, 0.745; 95% CI, 0.706 to 0.786) after adjusting for age, sex, smoking, alcohol consumption, exercise, low income, hypertension, dyslipidemia, body mass index, using insulin or oral antidiabetic drugs, and diabetic duration. A synergistically increased risk of LEA was observed with larger number of risky behaviors.
Conclusion: Modification of behaviors of current smoking, heavy alcohol intake, and exercise prevents LEA and can improve physical, emotional, and social quality of life in diabetic patients.

Background: Shift work is associated with obesity and metabolic syndrome. However, this association in the normal-weight population remains unclear. This study aimed to investigate whether shift work is associated with normal-weight obesity (NWO).
Methods: From the nationally representative Korea National Health and Nutrition Examination Survey (KNHANES) dataset (2008 to 2011), 3,800 full-time workers aged ≥19 years with a body mass index (BMI) ≤25 kg/m2 were analysed. We defined NWO as BMI ≤25 kg/m2 and body fat percentage ≥25% in men and ≥37% in women. Working patterns were classified into “daytime,” “other than daytime,” and “shift.” Multivariable logistic regression analysis was performed to evaluate the relationship between shift work and NWO.
Results: Shift work was associated with higher odds of NWO than daytime work (adjusted odds ratio [aOR], 1.47; 95% confidence interval [CI], 1.04 to 2.09) and night/evening work (aOR, 1.87; 95% CI, 1.11 to 3.14) after adjustment for type of work, working hours, age, sex, BMI, 25-hydroxyvitamin D levels, homeostatic model assessment for insulin resistance, and other sociodemographic factors. In subgroup analyses, the association between shift work and NWO was more robust in those aged ≥60 years and those working ≥56 hours/week.
Conclusion: Shift work was associated with NWO in community-dwelling Korean adults, independent of age, sex, BMI, and other covariates.

Background: In this study, we evaluated the recent changes in the standardized, age-specific, stage-specific incidence rates (IRs) of thyroid cancer in Korea and compared them with the incidence data reported by the Surveillance, Epidemiology, and End Results Program.
Methods: The analysis was conducted using the incidence data (2005 to 2018) from the Statistics Korea and Korea Central Cancer Registry.
Results: The age-standardized IR (SIR) of thyroid cancer increased from 24.09 per 100,000 in 2005 to 74.83 in 2012 (annual percent change [APC], 14.5). From 2012 to 2015, the SIR decreased to 42.52 (APC, -17.9) and then remained stable until 2018 (APC, 2.1). This trend was similar in both men and women. Regarding age-specific IRs, the IRs for ages of 30 years and older showed a trend similar to that of the SIR; however, for ages below 30 years, no significant reduction was observed from the vertex of IR in 2015. Regarding stage-specific IRs, the increase was more prominent in those with regional disease (APC, 17.4) than in those with localized disease until 2012; then, the IR decreased until 2015 (APC, -16.1). The average APC from 2005 to 2018 increased in men, those under the age of 30 years, and those with regional disease.
Conclusion: The SIR in Korea peaked in 2012 and decreased until 2015 and then remained stable until 2018. However, in young individuals under the age of 30 years, the IR did not significantly decrease but tended to increase again. In terms of stage-specific IRs, the sharpest increase was seen among those with regional disease.

Background: Excessive proliferation and migration of vascular smooth muscle cells (VSMCs), which contributes to the development of occlusive vascular diseases, requires elevated mitochondrial oxidative phosphorylation to meet the increased requirements for energy and anabolic precursors. Therefore, therapeutic strategies based on blockade of mitochondrial oxidative phosphorylation are considered promising for treatment of occlusive vascular diseases. Here, we investigated whether DN200434, an orally available estrogen receptor-related gamma inverse agonist, inhibits proliferation and migration of VSMCs and neointima formation by suppressing mitochondrial oxidative phosphorylation.
Methods: VSMCs were isolated from the thoracic aortas of 4-week-old Sprague-Dawley rats. Oxidative phosphorylation and the cell cycle were analyzed in fetal bovine serum (FBS)- or platelet-derived growth factor (PDGF)-stimulated VSMCs using a Seahorse XF-24 analyzer and flow cytometry, respectively. A model of neointimal hyperplasia was generated by ligating the left common carotid artery in male C57BL/6J mice.
Results: DN200434 inhibited mitochondrial respiration and mammalian target of rapamycin complex 1 activity and consequently suppressed FBS- or PDGF-stimulated proliferation and migration of VSMCs and cell cycle progression. Furthermore, DN200434 reduced carotid artery ligation-induced neointima formation in mice.
Conclusion: Our data suggest that DN200434 is a therapeutic option to prevent the progression of atherosclerosis.