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Pituitary gland pathology

Pituitary gland pathology. By Dr.Mays Ibraheem. Notes on normal histology and physiology of the pituitary gland. Small, bean- shaped structure that lies at the base of the brain within the sella turcica . It is connected by stalk to the hypothalamus.

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Pituitary gland pathology

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  1. Pituitary gland pathology By Dr.MaysIbraheem

  2. Notes on normal histology and physiology of the pituitary gland • Small, bean- shaped structure that lies at the base of the brain within the sellaturcica. It is connected by stalk to the hypothalamus. • The pituitary is composed of two morphologically & functionally distinct parts. (a) Anterior lobe (Adenohypophysis). Secretes hormones include PRL. TSH. ACTH.GTN. GH (b) Posterior lobe (Neurohypophysis). This lobe secretes two hormones ADH, OXYTOCIN.

  3. Pathology of pituitary gland Anterior lobe • Hyperpituitarism Adenoma • Hypopituitarism Ishemic necrosis (sheehans syndrome Posterior lobe • SIADAH(syndrome of inappropriate anti diruetic hormone) • Diabetes insipidus

  4. Pathology of anterior pituitary gland. Pituitary adenoma: • Non functional: bitemporalhemianopsia. • Functional tumor (hyperpituitarism): present with features depend on hormone produced. Classification of functional adenomas: 1. Prolactin cell adenoma 20%-30% 2. Growth hormone adenoma 5% 3. Mixed growth hormone / prolactin 5% 4. Adrenocorticotropic hormone cell adenoma 10%- 15% 5. Gonadotrophic hormone cell adenoma 10%- 15% 6. Null cell adenoma 20% 7. Thyroid stimulating hormone cell adenoma 1% 8. Other 15%

  5. Notes • The most common cause of hyperpituitarism is an adenoma arising in the anterior lobe. • Microadenomasare defined as less than 1 cm; macroadenomas are defined as more than 1 cm. Non-functional tumors are usually macroadenomas since they come to attention primarily due to mass effects • They are usually in adults; peak age incidence is between 4th & 6th decades

  6. Morphology of pituitary adenoma Well circumscribed, soft.Small adenomas are confined to sellaturcica. While larger tumors are extend to suprasellar region.

  7. Adenomas are composed of sheets or papillae of uniform cells with sparse support connective tissue.Nuclei of neoplastic cells are uniform or pleomorphic with scanty mitotic activity.Cytoplasm of neoplastic cells may be acidophilic, basophilic, or chromophobic

  8. prolactinoma • Most common type of hyperfunctioning pituitary adenoma, • These adenomas cause hyperprolactinemia. Which lead to different symptoms. In female cause amenorrhea and infertility, while in male cause galactorrhea. Causes of hyperprolactinemia 1. Adenomas. 2. Pregnancy. 3. High dose of estrogen treatment. 4. Renal failure. 5. Hypothyroidism. 6. Hypothalamic tumors. 7. Suprasellartmors that press the stalk between the pituitary & hypothalamus. 8. dopamine inhibitor drugs. Like reserpine.

  9. Growth hormone Adenomas • Secondmost common type of hyperfunctioning pituitary adenoma. • Usually macroadenoma at the time of diagnosis. • Secrete excess GH • In childhood, cause Gigantism (increase in size of body before the closure of epiphyseal plate. • While adultafter the closure of plate result in acromegaly (bone of the hand-sausage like finger- and face, & soft tissue enlargement) . • Diagnosis: increase GH and IGF1 lack of GH suppression by oral glucose.

  10. Hypopituitarism • Insufficient production of the hormone by the anterior pituitary gland. • Symptoms occur with loss or absence of 75% or more of the anterior pituitary parenchyma. • Clinical features of hypopituitarism: • Depend on the specific hormones that are lacking. Such as: • GH deficiency : Dwarfism (growth failure in children). • GnRH deficiency: Amenorrhea, infertility in women & loss of libido, impotence in male.

  11. Ischemic necrosis of the pituitary(Sheehanssyndrome) • Destruction of (>/= 75%) of the anterior pituitary parenchyma . • During pregnancy, anterior pituitary enlarges, because of increase number & size of prolactin secreting cells; however, this physiologic enlargement of the gland is not accompanied by an increase in blood supply, such enlarged gland is vulnerable to an ischemic injury in patient who develops significant hemorrhage & hypotension during peripartum period. • Come to attention with amenorrhea and loss of pubic hair.

  12. Posterior pituitary pathology • The clinically important posterior pituitary syndromes are. • Diabetes insipidus (Deficiency of ADH). • Secretion of inappropriately high level of ADH (SIADH).

  13. Secretion of inappropriate high level of ADH (SIADH). • A clinical syndrome characterized by excess ADH secretion. It causes reabsorption of excessive amounts of free water, with prominent hyponatremia. • ADH excess is caused by a number of extracranial & intracranial disorders. Causes. • Extracranial disorders: include ectopic ADH secretion by malignant neoplasms (particularly small cell carcinoma of the lung). • Intracranial disorders: trauma to the hypothalamus and / or pituitary

  14. Diabetes insipidus • A condition characterized by excessive urination (Polyuria) caused by inability of the kidney to properly reabsorb water from the urine. Due to deficiency of ADH. • Under normal condition, ADH acts on collecting ducts of kidney to promote water reabsorption from the urine. & so prevents the urination. • Causes • 1. Head trauma. • 2. Neoplasms & inflammatory disorders of hypothalamus & pituitary. • 3. Surgical procedures involving the hypothalamus or pituitary. • 4. Idiopathic.

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