This document discusses different types of thyroiditis including Riedel's, granulomatous, chronic lymphocytic, and subacute thyroiditis. It provides information on the etiology, pathology, clinical features, laboratory tests, age group, differential diagnosis, and treatment for each type. Riedel's thyroiditis is usually associated with mediastinal fibrosis and retroperitoneal fibrosis. Chronic lymphocytic thyroiditis most commonly affects females around menopause. Treatment options discussed include steroids, thyroxine supplementation, isthmusectomy if tracheal compression occurs, and subtotal thyroidectomy for large goiters.