A case report of unilateral development of painful thyroiditis used as a hallmark of the nervous nature of its pathogenesis.

Background: Painful thyroiditis (PT) combines several variants of pathology. The most common is subacute thyroiditis (ST). Despite the prevailing view that the factors underlying the development of ST have an infectious origin, its viral and bacterial pathogeneses remain unclear. Moreover, the hypothesis of genetic predisposition to ST is non-absolute. In previous studies, approximately 24-40% patients with ST manifested unilateral thyroid disease; however, the assessment of the pathogenesis of ST did not consider this fact. Case Description: This case of unilateral PT in a pregnant woman has become an illustrative example for revising the idea of its pathogenesis. Laboratory data did not show obvious signs of inflammation, which is typical for pregnant women and does not exclude ST. At the same time, rare in the literature illustrations of the ultrasound picture of unilateral PT are shown. Pathological parallels with other unilateral thyropathies have been drawn. A possible source of unilateral thyroid changes may be the nerve-conducting mechanism. Conclusions: The involvement of the nervous system in the inflammatory process and the possibility that unilateral nerve conduction affects only one of the thyroid lobes, as demonstrated in the present case, indicate that the autonomic nervous system (ANS) plays a leading role in PT development.