ACTA ENDOCRINOLOGICA (BUC)

Context. Despite CT being generally used in thymic pathology, in the case of regions with the same tissue density, only functional radioisotopic imaging can hint towards malignity. Objectives. To assess the usefulness of 99mTc MIBI scintigraphy for diagnosis and treatment planning in thymoma, in relation with the radiotracer uptake mechanism. Patients and methods. 99mTc MIBI thymic scans for 19 patients diagnosed with thymic disorders were assessed using tumor uptake ratio (UR). Specimens of thymectomies were examined and cytological assessments were correlated with the UR. Results. The UR of all surgical patients was higher than 1.2, with a 1.5 cutoff between lymphoid hyperplasia and thymoma. The UR values were correlated with the histopathologic diagnosis (Pearson correlation 0.91, significant at p<0.01). The highest UR was 3.24, found in the case of an AB thymoma where the rate lymphocytes/ epithelial cells (L/E) was 1.6. In B1 thymoma UR was 1.14 and L/E was 2.46. Conclusion. Phenotype differences between thymoma types correlate with 99mTc MIBI cellular uptake: lower rate L/E corresponds to higher UR, higher malignity potential and invasiveness. A thymic 99mTc MIBI UR higher than 1.5, corresponding to a CT tumoral image, is suggestive for a thymoma, requiring surgical treatment first.

Context. Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice. The increasing evidence supports links between inflammation and AF. There is evidence showing that obesity is a major cause of adipose tissue (AT) inflammation. Ghrelin (GHRL), through its growth hormone secretagogue receptor (GHS-R) present on adipose tissue macrophages (ATMs), could modulate AT inflammation. Objective. Our study aimed to evaluate the role of adipose tissue macrophages (ATMs) and their GHS-R in adipose tissue samples of right atrial appendages (RAA) biopsies. Subjects and Method. We obtained RAA biopsies from 10 obese patients, undergoing cardiac surgery for coronary artery bypass graft (CABG) and developing postoperative atrial fibrillation (POAF). The epicardial tissue samples were examined using immunohistochemistry to visualize and quantify CD68 and GSH-R expression of the ATMs. Results. Histologically, the mean adipocyte diameter (MAD) of epicardial adipose tissue (EAT) was larger in EAT samples with inflammation as compared to EAT without inflammation (84.2 μm vs. 79.6 μm). The expression of CD68 was lower in EAT without inflammation as compared to EAT with inflammation in adipose tissue samples. Similarly, the expression of GSH-R was lower in EAT samples without inflammation as compared to EAT samples with inflammation in adipose tissue. Conclusions. Increased epicardial fat area, macrophage infiltration, and GHS-R expression in epicardial ATMs appeared to be associated with postoperative atrial fibrillation in obese patients.