Solomon, Manyahelehal2021-07-142023-11-052021-07-142023-11-052014-12http://etd.aau.edu.et/handle/123456789/27159Background: The diversity of diseases affecting the thyroid gland can be due to hormonal excess/deficiency, reactive proliferations to deficiency states, inflammation, or neoplastic conditions most of which manifest by a form of enlargement of the thyroid gland commonly called goiter. The distribution of these diseases depends on several factors, both environmental and individual. Simple (non toxic goiter is quiet common throughout the world and is more prevalent where iodine difficiency is prevalent. The reported prevalence of goiter in Ethiopia is in the range of 27% in the early 90s to 40% today. Objective: To assess the distribution of histolpathologic types of thyroid diseases over a period of four years. Setting: Tikur Anbessa Specialized Hospital, Department of Pathology, College of Medicine and Health Sciences, Addis Ababa University Methods: Retrospective analysis of biopsy diagnoses of thyroid disease. Results: one thousand two hundred cases were included in the study. nine hundred eighty six were found to be non neoplastic(82%) and two hundred eleven were found to be neoplastic(18%). Nodular colloid goiter was the commonest, appearing in 956 cases(79.6%). Adenoma, carcinoma and thyroiditis accounted for 64(5.3%), 147(12.3%) and 16(1.3%)respectively. The female to male ratio was 5.1:1. Eighty four point five percent of thyroid diseases were found in the age group between 20 and 59 years. Conclusion: Nodular colloid goiter is the commonest of all thyroid diseases. Thyroid malignancies have become more common than adenomas. Papillary carcinoma is the commonest of thyroid cancers. Efforts need to improve to tackle the problem of iodine deficiency. Proper evaluation of thyroid swellings and early seeking of health service in case of neck swelling needs to be advocated.en-USThyroid,diseases,histopathologic diagnosisThesis