Quiz 3, Endocrine Flashcards
What occurs as a result of excess secretion of trophic pituitary hormones?
Hyperpituitarism
What is the most common cause of hyperpituitarism?
Adenoma arising in the anterior lobe
What occurs as a result of deficiency in one or more of the hormones produced by the pituitary gland?
Hypopituitarism
What are the causes of HYPERpituitism?
Pituitary adenoma
hyperplasia and carcinomas of the anterior pituitary
secretion of hormones by non-pituitary tumors
certain hypothalamic disorders
What are the causes of HYPOpituitarism?
Destructive processes such as: ischemic injury surgery or radiation inflammatory reactions non-functional pituitary adenomas
Expanding pituitary lesions often compress what? Causing what?
The decussating fibers in the optic chiasm causing visual field abnormalities, MC the lateral fields (bitemporal hemianopsia)
What is the size criteria for a pituitary adenoma being micro or macro? Which are more common?
> 10 mm
MC: Micro (16.7% of people, mostly undiagnosed)
T/F: ectopic pituitary adenomas are common.
False
They are rare tumors, occurring outside the sella turcica (usually in sphenoid sinus, suprasellar region, nasopharynx and the cavernous sinuses)
Why are silent and hormone-negative adenomas more likely to be macroadenomas, as opposed to micro?
Because they come to clinical attention at a later stage because they are not associated with endocrine abnormalities.
How are pituitary adenomas classified?
By what type of hormone is secreted by the tumor. (Tumors that don’t secrete any active hormone are still sometimes called chromophobic)
Based on plasma hormone levels or on immunohistochemical staining.
What is the peak age of incidence of pituitary adenomas?
35-60
What are the gross characteristics of a typical pituitary adenoma?
Soft, well-circumscribed lesion confined to the sella turcica.
What is the microscopic appearance of a pituitary adenoma?
Uniform polygonal cells arrayed in sheets or cords (cytoplasms may be acidophilic, basophilic, or chromophobic)
What distinguishes a pituitary adenoma from non-neoplastic anterior pituitary parenchyma?
The cellular monomorphism and the absence of a significant reticulin network.
What are the most frequent type of functioning pituitary adenomas, accounting for ~30% of all clinically recognized cases?
Prolactinoma (lactotroph adenoma)
Prolactinomas have a propensity to undergo what kind of changes?
Dystrophic calcification, ranging from isolated psammoma bodies to extensive calcification of virtually the entire tumor mass (pituitary stone)
Why are prolactinomas more readily diagnosed in women of childbearing age?
The hyperprolactinemia disrupts menses and causes amenorrhea, galactorrhea, loss of libido, and infertility. Men and menopausal women have more subtle symptoms which allows the tumors to reach considerable size
The majority of prolactinomas are composed of what type of cells?
Weakly acidophilic or chromophobic cells (sparsely granulated). Rarely, strongly acidophilic.
Adenomas of the anterior pituitary gland are a major clinical feature of what form of inherited endocrine disorder?
Multiple endocrine neoplasia type 1 (MEN 1)
What structures are most often affected by MEN syndromes?
Parathyroid glands
Pancreatic islet cells
Anterior lobe of the pituitary
What is pituitary apoplexy?
Acute hemorrhage or infarction into an adenoma (80% of cases involve previously undiagnosed adenomas)
What are the sxs of pituiray apoplexy?
Starts with a HA, then a rapidly worsening visual field defect. Then acute adrenal insufficiency sxs.
What is caused by necrosis of the pituitary gland due to blood loss and hypovolemic shock during and after childbirth?
Sheehan syndrome (postpartum hypopituitarism)
What causes Sheehan syndrome?
Hypertrophy and hyperplasia of lactotrophs during pregnancy results in the enlargement of the anterior pituitary without a corresponding increase in blood supply. It is also supplied by a low pressure portal venous system that is vulnerable to hemorrhages or hypotensions leading to ischemia. (posterior pituitary is not effect due to its direct arterial supply)
T/F: empty sella is gangsta’ slang for “we’re out of wine”
False! It means the sella turcica is without its homey, the pituitary gland. It just gets filled with CSF.
T/F: Amyloid deposits may be seen in pituitary adenomas in the absence of amyloidosis.
True
What are the two most common hypothalamic suprasellar tumors?
Gliomas and craniopharyngiomas
What is the most common sellar tumor in children? Hint: it’s benign but locally invasive and originates from remnants of Rathke’s pouch.
Craniopharyngioma (bimodal age distribution; 5-15 and 65+)
What are the microscopic characteristics of craniopharyngiomas?
Expanding mass arising in the sella turcica that erodes bone and infiltrates into surrounding structures. Appear as squamous and columnar epithelium lining cystic space filled with oily fluid and “wet keratin”.
Although pituitary adenomas are widely invasive, destructive of adjacent tissues, and lethal, they are not classified as malignancies. How are malignant tumors of adenohypophyseal origin defined?
Their ability to metastasize
What are the two most common sources of cancer that metastasizes to the pituitary?
Breast and lung cancers
What is the literal translation of “filet mignon”?
Cute cut
What are some of the effects of T3 excess?
Increased HR vasodilation warm, smooth, moist skin Increased GI motility Increased bone turnover Increased muscle contraction
What are the conditions most notable for causing a HYPOthyroid state?
Hashimoto's Acute thyroiditis Subacute " Infiltrative " Postoperative Iatrogenic
What is the most common cause of hypothyroidism?
Autoimmune lymphocytic thyroiditis (Hashimoto’s)
What is the relationship of iodine to the thyroid gland?
Iodine is essential for the production of thyroxine. If deficient in the diet, the thyroid becomes enlarged (goiter)
One cause of HYPERthyroidism is the conscious or accidental ingestion of excess quantities of thyroid hormone. What is this called?
Thyrotoxicosis factitia
What are some of the conditions that cause HYPERthyroidism?
Grave's dz Toxic thyroid nodule Plummer's dz (toxic multinodular goiter) Iatrogenic hyperthyroidism Thyroid storm
What condition is an autoimmune dz in which the thyroid gland is attacked by a variety of cell and antibody mediated immune processes?
Hashimoto’s thyroiditis
What is the cause of thyroid enlargement in Hashimoto’s?
Lymphocytic infiltration and fibrosis (not hypertrophy)
Physiologically, antibodies against what, causes gradual destruction of follicles in the thyroid gland with Hashimoto’s?
Thyroid peroxidase (TPO) and/or thyroglobulin
What is the gross appearance of Hashimoto’s thyroiditis?
Cut surface may have “fleshy” appearance
Retrosternal extension
Enlargement is not necessarily symmetrical
Lobulated pattern
Scattered tiny nodules of darker tan colored glassy material (residual colloid)
T/F: Hashimoto’s can cause both HYPER and HYPOthyroidism
True: Early on it causes hyper, than goes through euthyroid stage. Eventually atrophy of the gland results in hypothyroidism.
What is a cell that often appears in thyroid tissue of patients with Hashimoto’s or follicular thyroid cancer?
Hurthle cell
What do Hurthle cells look like?
Enlarged epithelial cells which generally stain pink with abundant eosinophilic granular cytoplasm as a result of altered mitochondria
Does subacute thyroiditis cause HYPO or HYPERthyroidism?
Either
What histologic finding is characteristic of de Quervain’s disease (sub-acute thyroiditis)?
Granulomas (Multinucleated giant cells)
What is the most common location for a thyroglossal cyst?
Between the isthmus of the thyroid and the hyoid bone
What is the most common type of congenital neck malformation and what causes it?
A thyroglossal duct cyst caused by duct being persistent (failing to close) during embryonic development. It becomes fluid filled.
T/F: Thyroid nodules are rare and indicate malignancy.
False. They are common, but benign (95%).
Non-toxic multinodular goiter is compatible with euthyroid state. What is seen microscopically if the follicles are irregularly enlarged?
They are usually surrounded with flattened epithelium, consistent with inactivity of the thyroid.
A toxic nodular goiter (TNG) is a thyroid gland that contains what? (aka Plummer’s dz)
Autonomously functioning thyroid nodules resulting in hyperthyroidism