Association and similarities between undifferentiated connective tissue diseases and autoimmune thyroid diseases

Abstract

Objectives: Autoimmune thyroid diseases (ATDs) can be accompanied by systemic autoimmune diseases. The aim of this study was to determine the association, similarities, and differences between undifferentiated connective tissue diseases (UCTDs) and ATDs. Materials and Methods: Fifty-nine UCTD patients and 108 control subjects were retrospectively evaluated. Thyroid function tests, antithyroid antibodies, antinuclear antibody (ANA), anti-double stranded deoxyribonucleic acid and anti-extractable nuclear antigens peptide levels, and histopathological examination of the minor salivary gland were evaluated. Results: The prevalence of ATD was 23.70% and 33.30% in the UCTD and control groups, respectively (p = 0.220). The prevalence of arthritis in isolated UCTD patients was 11.10%, which was significantly increased (35.70%) if UCTD was accompanied by a ATD (p = 0.047). Other clinical symptoms such as arthralgia, xerostomia, keratoconjunctivitis sicca, Raynaud's phenomenon, oral aphthous ulcers, and photosensitivity observed in UCTD, ANA positivity rates, and the most common staining pattern (speckled) were similar between the ATD and non-ATD patients. Histopathological examination of the minor salivary gland in 9 ATD patients revealed no significant lymphocyte infiltration. In the comparison of UCTD and ATD patients, the findings were similar, except arthralgia and ANA positivity, which were higher in UCTD patients. Conclusion: As a result, considering similar clinical symptoms and autoimmune profiles of UCTD and ATD, it is recommended to make a clear differential diagnosis of both diseases in patients presenting with complaints such as arthralgia, xerostomia, and Raynaud's phenomenon.