Association of Autoimmune Thyroiditis with Thyroid Dysgenesis

Abstract

Introduction: The thyroid gland is bilobed, with isthmus bridging the two lobes. The thyroid gland develops from the thyroglossal duct, which arises from the foramen caecum as an endodermal thickening during 3th week of intrauterine life, which reaches its definitive position by the seventh week. The high division of the thyroglossal duct can lead to the creation of two distinct lateral thyroid lobes and the absence of the thyroid isthmus. Hence, agenesis of the thyroid gland can be linked to its early embryonic development. Thyroid dysgenesis is also clinically associated with autoimmune thyroiditis (e.g. Hashimoto’s thyroiditis), dysorganogenesis, and ectopic thyroid tissue. Aim: To establish an association of Autoimmune thyroiditis with thyroid dysgenesis. Settings and Design: Descriptive observational study. Methods and Material: A study was conducted on 51 formalin fixed cadaveric thyroid glands over twenty months. After carefully dissecting the anterior aspect of the neck, the thyroid glands with absent isthmus were identified and subjected to histological examination. Statistical analysis used: Statistical analysis and sample size calculation was done using formula for prevalence as per previous studies. Results: Out of 51 thyroid glands, five glands (9.8%) were found to have absent isthmus and were subjected to haematoxylin and eosin (H&E) staining. All glands demonstrated the presence of diffuse lymphocytic infiltration and atretic thyroid follicles. Three glands showed the presence of hurthle cells, empty thyroid follicles along with diffuse lymphocytic infiltration which are typical histological features of autoimmune thyroiditis. Conclusions: The present study of thyroid dysgenesis can be histologically correlated with Autoimmune thyroiditis due to the presence of specific features, such as hurthle cells, diffuse lymphocytic infiltrate, atretic and empty thyroid follicles as seen in 10X and 40X magnification in all five glands. All of the above histological findings are typically seen in auto immune thyroiditis.