MYOFIBROBLASTS HINDER RECOVERY OF HASHIMOTO THYROIDITIS IN THE ULTRASTRUCTURAL LEVEL.

Background: Hashimoto thyroiditis (HT) is an autoimmune disorder associated with hypothyroidism. Lymphocyte infiltration leading to thyroid follicular cell destruction is counteracted by increased collagen production, deposition and scarring. However, only recently a specific subpopulation of modified fibroblasts with contractile properties, namely "myofibroblasts" (MFBs) have been linked to HT. Aim: Our ultrastructural study aims to delineate the presence and contribution of MFBs to the fibrotic milieu of HT. Material and Methods: Tissue biopsies were obtained from 5 HT-diagnosed patients and specimens were examined using a Transmission Electron Microscope (TEM). Results: Histopathological examination indicated extensive microvilli atrophy and atypical vacuolations of the thyroid follicular cells in the HT samples. In addition to interstitial extravasated lymphocytes, capillaries were encircled by MFBs (mean distance from lumen 1.248± 0.43µm) with the characteristic electron-dense α-smooth muscle actin (α-SMA), confirmable in higher magnifications. Myofibroblastic projections were found to have significantly higher representation near the capillary lumen compared to the impaired endothelial lining (P < 0.01). Conclusion: Our TEM findings suggest that the intrusion of endothelia by myofibroblastic projections can be a significant factor towards the malfunction of follicular cells in HT patients and offer a paradigmal understanding of the ultrastructural interactions that may underlie the HT pathology.

Identifying erroneously used terms for vascular anomalies: A review of the English literature.

Background: The classification of vascular anomalies includes terms of nomenclature that are not based on histogenesis resulting in confusion among health professionals of different specialties. Ongoing efforts to classify them properly have taken place. This literature review aimed to identify erroneous nomenclature of vascular anomalies and to investigate their continued use over the past four years after the last International Society for the Study of Vascular Anomalies (ISSVA) update. Methods: Literature research was based on pertinent classifications (ISSVA, WHO) and books related to vascular anomalies and soft tissue pathology. After identifying twelve entities with confusing terminology, new research in the Pubmed database was conducted to verify their continued use in the last four years. Results: The literature review highlighted terms referring to vascular malformations as neoplasms. In addition, terms used as equivalents represent entirely different entities. On the other hand, different terms to characterize the same entity were also recorded. Furthermore, regardless of the last ISSVA update in 2018, terms that are only descriptive or do not correspond to vascular anomaly histogenesis are consistently used. Conclusion: Despite intensive efforts in the last decades for correct terminology and classification of vascular anomalies, modifications are still required. A common and broadly accepted scientific terminology should be applied, accurately representing histogenesis or pathogenesis, to obtain a common language among medical specialists, given that a multidisciplinary approach is crucial for managing vascular anomalies. HIPPOKRATIA 2022, 26 (4):126-130.