بسم هللا الرحمن الرحيم THYROID GLAND By Dr. Ghada Ahmed Lecturer of pathology Benha Faculty of Medicine Normal thyroid Hypothalamic-pituitary-thyroid axis Hypothyroidism Primary hypothyroidism Thyroiditis :Hashimoto autoimmune thyroiditis Dietary iodine deficiency. Drugs that block thyroid hormone synthesis. Thyroid surgery or radiation. Secondary hypothyroidism: usually caused by TSH deficiency. Hypothyroidism Clinical effects: Cretinism Hypothyroidism Myxdema Hyperthyroidisim (Thyrotoxicosis) Primary hyperthyroidism: Graves disease (autoimmune)(85% of cases). Goiter: Hyperfunctional multinodular goiter. Adenoma: Hyperfunctional adenoma of thyroid. Secondary hyperthyroidism: Pituitary adenoma. Inappropriate intake of exogenous hormone (as a treatment for hypothyroidism) Hyperthyroidisim (Thyrotoxicosis) Clinical features: Cardiac manifestations Ocular manifestations Neuromuscular system Skin Gastrointestinal system Low serum TSH with increased free serum T4. Thyroiditis Types: Hashimoto thyroiditis Subacute (granulomatous) thyroiditis Reidel thyroiditis Hashimoto thyroiditis Hashimoto thyroiditis Subacute (granulomatous) thyroiditis History of upper respiratory tract infection Reidel thyroiditis Rare disease. Unknown etiology. Extensive fibrosis of thyroid and surrounding neck structures. Graves disease Pathogenesis It results from autoantibodies to TSH receptor, (long acting thyroid stimulator (LATS)) activate the surface receptors for TSH on thyroid epithelium. Graves disease Pathogenesis Gross picture Microscopic picture Graves disease Graves disease Clinical effects Goiters Definition Goitrogens Types of Goiter Diffuse (non toxic) Goiter Multinodular (toxic / non toxic) Endemic Sporadic Diffuse nontoxic (simple) goiter Endemic form Sporadic form Morphology: Hyperplastic stage Colloid involution stage Most patients are clinically euthyroid. Multinodular goiter (Nodular colloid goiter) Repeated cycles of stimulation and involution of a diffuse goiter Pressure symptoms It may be non-toxic or may induce thyrotoxicosis (toxic multinodular goiter). Multinodular goiter (Nodular colloid goiter) Multinodular goiter (Nodular colloid goiter) Tumors of the thyroid gland A) Benign tumors: Follicular adenoma B) Malignant tumors Thyroid carcinoma Benign tumors thyroid follicular adenoma Benign tumors thyroid follicular adenoma Microscopic picture: various histologic subtypes according to degree of follicle formation and colloid content: 12345- Colloid adenoma (macrofollicular). Fetal adenoma (microfollicular). Embryonal adenoma. Hϋrthle cell adenoma. Atypical adnoma. Benign tumors thyroid follicular adenoma Thyroid follicular adenoma Clinical effects: Thyroid carcinoma Papilary carcinoma Follicular carcinoma Medullary carcinoma Anaplastic carcinoma Papillary carcinoma Papillary carcinoma Follicular carcinoma Follicular carcinoma Capsular invasion in follicular carcinoma Vascular invasion in follicular carcinoma Medullary carcinoma Medullary carcinoma Anaplastic carcinoma Anaplastic carcinoma Thyroid Nodule Thyroid nodule Nonneoplastic Nodular colloid goiter Hashimoto thyroiditis Neoplastic Adenoma carcinomas