BRS Pathology - Chapter 20 - Endocrine System

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Most common pituitary tumor? % of all pituitary tumors?: Prolactinoma with hyperprolactinemia makes up 30% of pituitary tumors.
Characteristics of prolactinoma?: Most common pituitary tumor
Chromophobic staining
In women, leads to amenorrhea, galactorrhea
Undergoes dystrophic calcification
Underlying cause for 1/4 cases of amenorrhea
Treatment for prolactinoma?: Most commonly bromocriptine: a dopamine receptor agonist that causes the lesion to shrink

Surgery
What hypothalamic factors control release of the following pituitary hormones: TSH, PRL, ACTH, GH, FSH, LH? Is the controlling factor stimulatory or inhibitory for each?: TSH: stimulated by TRH, inhibited by somatostatin
Prolactin: inhibited by dopamine
ACTH: stimulated by CRH
GH: stimulated by GHRH, inhibited by somatostatin
FSH: stimulated by GnRH
LH: stimulated by GnRH
Characteristics of somatotropic adenoma?: Second most common pituitary tumor
Acidophilic staining
Causes release of somatomedins by liver (IGF-I, somatomedin C)
Causes gigantism if during childhood, acromegaly during adulthood.
Causes local compression in sela turcica.
Characteristics of corticotropic adenoma?: Hypercorticism (Cushing disease)
Basophilic staining
Weight gain, moon facies, thin/atrophied skin, hirsuitism, HTN, hyperglycemia due to insulin resistance
Difference between Cushing disease and Cushing syndrome?: "Syndrome" is hypercorticism regardless of cause, "disease" is in the case of corticotropic adenoma of the pituitary.
What is pituitary cachexia (Simmonds disease)? What are the 2 most common causes?: Generalized panhypopituitarism leading to marked wasting.

Pituitary tumors and Sheehan's syndrome (postpartum pituitary necrosis) are the most common causes.
What is Sheehan's syndrome?: Ischemic necrosis of the pituitary during child birth, due to hypoperfusion. The pituitary enlarges during pregancy but its blood supply does not... hence it is suspectible to peripartum blood loss.
Symptoms of growth hormone deficiency?: In children: growth retardation
In adults: increased insulin sensitivity with hypoglycemia, decreased muscle strength, and anemia.
Symptoms of gonadotropin deficiency?: In children: retarded sexual maturation
In adult men: loss of libido/muscular mass, impotence, decreased body hair
In adult women: amenorrhea, vaginal atrophy
Result of TSH deficiency?: Secondary hypothyroidism.
How to distinguish between deficiency of ACTH and primary adrenal failure (Addison disease)?: In Addison disease B-melanocyte stimulating hormone is still high leading to hyperpigmentation of skin. Not true in ACTH deficency, where B-MSH is also low.
Function of oxytocin?: Induces uterine contraction during labor, ejection of milk from mammary alveoli
Most common cause of SIADH?: Small cell carcinoma of lung.

Other tumors can also produce ectopic ADH.
Causes of ADH deficency (diabetes insipidus)?: Tumors
Trauma
Inflammatory processes
Lipid storage disorders
etc.
What is empty sella syndrome?: Pituitary hypofunction due to destruction of all or part of the pituitary.
What is Nelson syndrome?: Large pituitary adenomas that develop after bilateral adrenalectomy: due to a loss of feedback inhibition on preexisting pituitary microadenomas.
What hormones are released by the neurohypophysis? Is it anterior or posterior?: Oxytocin, ADH
Posterior
What hormones are released by the adenohypophysis? Is it anterior or posterior?: TSH, prolactin, ACTH, GH, FSH, LH
Anterior
What is a craniopharyngioma?: Benign childhood tumor from remnants of Rathke pouch.
Often cystic or calcified.
Not a true pituitary tumor, but can have mass effects that cause pituitary hypofunction.
What are the symptoms of a nonsecreting pituitary adenoma or other mass lesion in the sella?: Hypopituitarism, headache, visual disturbances (bilateral hemianopsia due to optic chiasm pressure) and palsies (due to cranial nerve compression)
What is the most common congenital anomaly of the thyroid? other anomalies?: thyroglossal duct cyst; it does not lead to alterations in thyroid function.

Ectopic thyroid tissue may also be found anywhere along the course of the thyroglossal duct. (If removing these, be sure they are not the ONLY thyroid tissue!)
what are the causes of goiter?: physiologic enlargement during puberty and pregnancy
iodine deficiency
Hashimoto thyroiditis
goitrogens: substances that suppress synthesis of thyroid hormones
dyshormonogenesis: failure of hormone synthesis due to enzyme defects
what is the difference between a hot nodule and cold nodule in the thyroid?: most nodules are hypoplastic and do not take up radioactive iodine (cold)

Some nodules are hyperplastic and actively produce thyroid hormone, and take up radioactive iodine (hot)

Nonfunctional (cold) nodules are more likely to be malignant compared to functional (hot) nodules.
what are the causes and characteristics of myxedema?: Therapy for hyperthyroidism, Hashimoto thyroiditis, idiopathic, iodine deficiency

Clinical characteristics include cold intolerance, weight gain, low voice, mental slowness, menorrhagia, constipation, dry skin, hair loss, puffiness of the face
what are the causes and characteristics of cretinism?: Iodine deficiency, thyroid enzyme deficiency, poor thyroid development, failure of fetal thyroid dissent, trans placental transfer of antithyroid antibodies from a mother with autoimmune thyroid disease

Characteristics include severe mental retardation, impaired physical growth and dwarfism, a large tongue, and a protuberant abdomen
what are the symptoms of hyperthyroidism (thyrotoxicosis)?: Restlessness, irritability, fatigability, tremor, heat intolerance and sweating, tachycardia, muscle wasting and weight loss, fine hair, diarrhea, menstrual abnormalities, and most importantly greatly increased T4.
what is Graves' disease? What is its mechanism? Susceptible individuals?: Hyperthyroidism caused by a diffuse toxic goiter. It occurs more frequently in women than in men, and the incidence is increased in HLA-DR3 and HLA-B8 positive individuals. Exophthalmos is characteristic and unique.

Autoimmune disease, with thyroid stimulating immunoglobulin (TSI) and thyroid growth immunoglobulin (TGI) causing hormone production and hyperplasia.
what are the three types of thyroiditis?: Hashimoto thyroiditis
subacute granulomatous thyroiditis
Riedel thyroiditis
What is Hashimoto thyroiditis? Who is susceptible?: Autoimmune disorder, common cause of hypothyroidism. Histologically, massive infiltrates of lymphocytes with germinal center formation and Hurtle cells. Autoantibodies are present, including anti-thyroglobulin, antithyroid peroxidase, anti-TSH receptor, and anti-iodine receptor.
Associated with increased incidence of pernicious anemia, diabetes mellitus, and Sjogren's syndrome. Associated with HLA-DR5 and HLA-B5.
What is subacute granulomatous thyroiditis? What appears to be a common cause?: focal destruction of thyroid tissue and granulomatous inflammation caused by a variety of viral infections, including mumps and Coxsackie virus.

Follows a self-limiting course of several weeks duration consisting of a flulike illness, pain and tenderness of the thyroid, and a transient hyperthyroidism.
what is Riedel thyroiditis?: Idiopathic replacement of the thyroid by fibrous tissue, can mimic carcinoma.
What are the characteristics of papillary carcinoma of the thyroid? Common causes?: the most common thyroid cancer
Histologically: papillary projection into gland-like spaces, empty "orphan Annie" nuclei, calcified spheres
excellent prognosis, even when the adjacent lymph nodes are involved
can be caused by long-term radiotherapy to the neck, or RET-PTC fusion gene
List the four types of malignant thyroid tumors. Which has the best prognosis and which has the worst?: papillary carcinoma - best
follicular carcinoma
medullary carcinoma
undifferentiated carcinoma -worst
what are the characteristics of medullary carcinoma of the thyroid?: Originates from C-cells in the thyroid, produces calcitonin.
histologically: sheets of tumor cells in amyloid stroma
associated with multiple endocrine neoplasia II, III
What are the causes of primary hyperparathyroidism? What are the laboratory findings associated with it? What are the clinical manifestations?: Most common cause is parathyroid adenoma. Primary parathyroid hyperplasia and carcinoma are less likely. PTH-like hormone can be produced by bronchogenic squamous cell carcinoma or renal cell carcinoma.
Lab findings include hypercalcemia/hypercalciuria, decreased serum phosphorus/increased urinary phosphorus, increased serum alk.phos., and increased serum PTH.
Clinical symptoms include cystic bone changes, "metastatic calcification", renal calculi, peptic ulcer.
What are the causes of secondary hyperparathyroidism? What are the lab values and clinical characteristics?: Commonly caused by hypocalcemia in chronic renal disease. Vitamin D conversion by the kidney is impaired, decreasing intestinal absorption of calcium.

Lab values include decreased serum calcium, increased serum phosphorus, increased serum alkaline phosphatase, increased serum PTH. Clinical symptoms include osteoclastic bone disease and metastatic calcification.

(Personal note: many apparent paradoxes in this disease)
What causes hypoparathyroidism? What are the symptoms?: The most common cause is accidental surgical excision during thyroidectomy. Sometimes associated with congenital thymic hypoplasia (DiGeorge syndrome).
Resulting in severe hypocalcemia, manifested as increased neuromuscular excitability and tetany.
What is pseudo-hypoparathyroidism?: Multi-hormone resistance including PTH, and the pituitary hormones TSH, LH, and FSH.
Clinical characteristics include unresponsiveness of the kidney to PTH, shortened fourth and fifth metacarpal and metatarsals, short stature, and other skeletal abnormalities.
What are the causes of Cushing's syndrome? What is the difference between Cushing's syndrome and Cushing's disease?: Exogenous corticosteroid medication
Hyper production of ACTH by pituitary adenoma
Adrenal cortical adenoma or carcinoma
Ectopic production of ACTH (by small cell carcinoma of the lung)

Cushing's syndrome results from increased circulating cortisol from any source, Cushing's disease refers to only hyper production of ACTH by pituitary adenoma.
What is primary hyperaldosteronism?: Conn syndrome, usually due to an aldosterone producing adrenocortical adenoma or carcinoma.
Causes hypertension, sodium and water retention, and hypokalemia.
Decreased serum renin is present due to negative feedback from hypertension.
What is secondary hyperaldosteronism?: Caused by stimulation of the renin angiotensin system. Serum renin is increased in contrast to primary hyperaldosteronism.
Usually secondary to renal ischemia, renal tumors, and edema (cirrhosis, nephrotic syndrome, cardiac failure).
What is adrenal virilism?: Congenital enzyme defects that lead to diminished cortisol production and compensatory increased ACTH. This leads to adrenal hyperplasia and androgenic steroid production.
Deficiencies include 21-hydroxylase deficiency and 11-hydroxylase deficiency.
Clinical characteristics include precocious puberty in males and virilism in females.
What is Addison disease? Symptoms and labs?: Primary adrenocortical deficiency, usually due to idiopathic adrenal atrophy. Can also be caused by tuberculosis, metastatic tumor, and infection. Characteristics include hypotension, skin pigmentation, low serum sodium, chloride, glucose, bicarbonate and increased potassium.
What is Waterhouse-Friedrichsen syndrome?: Catastrophic adrenal insufficiency and vascular collapse due to hemorrhagic necrosis of the adrenal cortex. Often associated with DIC and characteristically due to meningococcal meningitis (Neisseria meningitis).
What is a pheochromocytoma?: Adrenal medulla tumor of chromaffin cells. Causes paroxysmal hypertension due to hyperproduction of catecholamines. Increased urinary excretion of catecholamines and metabolites (metanephrine, normetanephrine, vanillylmandelic acid). Can also cause hyperglycemia.
What is a neuroblastoma?: A highly malignant catecholamine producing tumor occurring in early childhood. Urinary catecholamines and metabolites are seen as in pheochromocytoma. Hypertension is common. Originates in the adrenal medulla and presents as a large abdominal mass.
Epidemiology and etiological factors of type 1 diabetes mellitus?: Usually early in life, less common than type 2 disease. The disease is due to failure of insulin synthesis by beta cells of the pancreatic islets. Cause may be due to genetic predisposition or autoimmune inflammation of the islets. Incidences significantly higher in individuals with a mutation in HLA DQ, and in HLA DR3/HLA DR4 positive individuals.
Clinical characteristics of type 1 diabetes?: Without insulin replacement: carbohydrate intolerance with hyperglycemia leading to polyuria, polydipsia, weight loss, ketoacidosis, coma, and death. Ketoacidosis results from increased metabolism of fat leading to production of "ketone bodies".
Epidemiology and etiological factors of type 2 diabetes mellitus? Causes of secondary type 2 diabetes?: Type 2 is much more common than type 1, and tends to begin in middle age. Positive family history is often present. Type 2 disease is due to increased insulin resistance, and is associated with obesity.

Type 2 can also occur as a secondary phenomenon in certain conditions including:
pancreatic disease -- hemochromatosis, pancreatitis, pancreas carcinoma
other endocrine -- Cushing's, acromegaly, glucagon hypersecretion, pheochromocytoma, hyperthyroidism
pregnancy -- gestational diabetes, hyperglycemic mother leads to infants with hyperplastic islets
Anatomic changes in diabetes mellitus?: Kidney: widened glomerular basement membrane, glomerulosclerosis, exudative lesions, pyelonephritis.
Cardiovascular: atherosclerosis, MI, peripheral vascular disease, capillary basement membrane thickening
Eye: cataract formation, proliferative retinopathy (exudates, edema, hemorrhage, micro aneurysms)
Nervous system: peripheral neuropathy
Liver: fatty changes
Skin: xanthomas, infections
What is an insulinoma?: A beta cell tumor, the most common islet tumor. Characterized by insulin secretion with high levels of C-peptide. Symptoms include Whipple's triad: paroxysmal hypoglycemia, CNS dysfunction (confusion, anxiety, coma, convulsions), immediate recovery with glucose administration
What is a gastrinoma?: Gastrin secreting tumor, often malignant and sometimes found outside the pancreas.
Causes gastrin hypersecretion and hypergastrinemia.
Causes Zollinger-Ellison syndrome (high gastric HCl, PUD, hypergastrinemia)
What is a glucagonoma?: A glucagon secreting alpha cell tumor that causes secondary diabetes mellitus. Also causes a skin lesion called necrolytic migratory erythema in 80% of cases, a spread of erythematous blisters and swelling across areas subject to greater friction and pressure, including the lower abdomen, buttocks, perineum, and groin.
What is a VIPoma?: Vasoactive intestinal peptide secreting tumor. Causes watery diarrhea, hypokalemia, and achlorhydria syndrome (pancreatic cholera).
What is MEN-1?: Werner syndrome: hyperplasia or tumors of the pituitary, parathyroid, and pancreatic islets (3 Ps). May also involve the thyroid and adrenal cortex. Linked to mutations in the MEN-1 gene (chr 11).
Pancreatic component includes ZE syndrome, insulinoma, or pancreatic cholera.

autosomal dominant
What is MEN-2a?: Sipple syndrome, includes pheochromocytoma, medullary carcinoma of the thyroid, and hyperparathyroidism due to hyperplasia or tumor. Due to mutation in the ret oncogene on chromosome 10.

autosomal dominant
What is MEN-2b (MEN-3)?: Characterized by pheochromocytoma, medullary carcinoma, and multiple mucocutaneous neuromas. Unlike MEN-2a no hyperparathyroidism. Linked to mutations in the ret oncogene on chromosome 10.

autosomal dominant

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