Chapter 29 - Endocrine System Tumors
What are some prognostic factors associated with thyroid cancer?
age, gender, histologic subtype, and capsular invasion
Graves Disease
an inherited autoimmune disease characterized by a high metabolic rate, abnormal weight loss, excessive perspiration, muscular weakness, emotional instability, and exophthalmos (protrusion of the eyeball)
Nodal Sites Around The Thyroid Gland
internal jugular chain, Delphian node (anterior cervical node), pre-tracheal nodes, and paratracheal nodes in the lower neck; if superior mediastinal lymphatics are involved it represents significant regional spread
Pituitary Tumors
less aggressive than many CNS tumors, although still pose problems as a result of local growth that causes compressive and destructive effects and endocrine abnormalities cause by pituitary hormone dysfunction; the pituitary is composed of an anterior, a posterior, and an intermediate lobe (anterior portion is most common site)
Pituitary Tumor Staging
most are benign so no true staging system exists; these are graded (there are 4 grades)
Thyroid Cancer Epidemiology
most common endocrine malignancy (accounts for 94%); but only represents 2% of all cancers
What are the four categories of malignant thyroid neoplasms?
papillary, follicular, medullary, and anaplastic
The pituitary gland produces many hormones under the influence of the what?
the hypothalamus
What can an ultrasound determine?
whether the nodule is solid or cystic
Anaplastic Carcinoma
carries the worst overall prognosis; most aggressive type; life expectancy is typically a year or less
Oxytocin
causes smooth muscle contraction
What are the three ways a thyroid nodule can be imaged?
cold thyroid nodule (no radionuclide uptake), warm thyroid nodule (slightly higher concentration than the rest of the thyroid gland), and hot thyroid nodule (radionuclide uptake much higher than the rest of the thyroid gland)
The Endocrine System
composed of multiple glandular organs responsible for complex metabolic regulatory functions
Isthmus
connects the two thyroid gland lobes in the midline at the level of the second to fourth tracheal rings
Anatomy of The Thyroid Gland
consists of a right and left lobe; lies over the deep structures of the neck; close to the larynx, trachea, parathyroid glands, and esophagus; it is anterior and medial to the carotid artery, jugular vein, and vagus nerve; the two large lateral lobes are about 5cm in length and extend to the level of the mid-thyroid cartilage superiorly and the sixth tracheal ring inferiorly
GH (growth hormone)
controls body growth
TSH (thyroid-stimulating hormone)
controls the thyroid gland
What are some disorders associated with hypothyroidism?
cretinism and myxedema
Pituitary Tumor Prognosis
depends on type of adenoma and other factors
Adenohypophysis
derived from the endoderm, this forms the glandular part of the pituitary
Dysphagia
difficulty swallowing
Adrenal Cortex Tumor Clinical Presentation
due to location many patients have symptoms of pain which develops from advanced disease; there may also be symptoms of excess hormone production
Thyroid Cancer Routes of Spread
each pathology has its own route; Papillary metastasize to regional lymph nodes through lymphatic channels and can also spread through blood; Follicular tend to invade vascular channels and metastasize via the bloodstream to distant sites including bone, lung, liver, and brain & lymph travel is uncommon; Medullary starts by spreading regionally and then metastases can occur hematogenously or through lymph with main sites being cervical nodes, lung, liver, and bone; Anaplastic spreads locally to structures like the trachea or skin & regional neck nodes are often involved
Diffuse Pituitary Adenomas
fill the entire sella and can erode its wall
Neoplasms
formed of tightly packed cells that remain separate from healthy tissue without a membrane and are classified according to size
What are some disorders associated with hyperthyroidism?
graves disease and goiters
Macro-adenomas
greater than 10 mm
Intrasellar Pituitary Tumors
grow within the confines of the sella
What is the second most common functioning pituitary tumor?
growth hormone secreting adenoma; these result in acromegaly (enlarged extremities) in adults and gigantism in children
Invasive Pituitary Tumors
have a more rapid growth rate and tend to erode outside the sella to invade neighboring tissues such as the posterior pituitary gland, sphenoid bone, and cavernous sinus
Functional disorders of the thyroid gland are characterized by what?
hyperactivity (hyperthyroidism) or under-activity (hypothyroidism)
Non-Functioning Pituitary Adenomas
if they arise from the gonadotropin-producing cells then they are not associated with the classical hyper secretion syndrome
Lesions in the thyroid gland should arouse suspicion if what?
if they exhibit extreme hardness, appear fixed to deep structures or skin, or are associated with hoarseness from recurrent laryngeal nerve paralysis
What are some possible side effects of iodine-131 treatment?
inflammation of salivary glands, nausea, vomiting, fatigue, and bone marrow suppression
ACTH (adrenocorticotrophic hormone)
influences the action of the adrenal cortex
PRL (prolactin)
initiates milk production
What are specialized cells in the pancreas called?
islets of Langerhans
Micro-adenomas
less than 10 mm
What type of surgery can be used for lateralized thyroid cancers?
lobectomy including removal of isthmus
Bitemporal Hemianopsia
loss of peripheral vision bilaterally
The Cortex
manufactures steroid hormones that are critical to metabolic regulation
Malignant Pituitary Adenomas
metastasize via CSF or vascular pathways (this is rare though)
How is thyroid cancer diagnosed?
most important: biopsy; also will use specialized imaging studies and laboratory testing
Adrenal Cortex Tumor Prognosis
most patients have advanced disease at the time of diagnosis; the ability of the surgeon to completely resect is a huge prognostic factor; a young age at the time of diagnosis is a better prognosis
Clinical Presentation of Thyroid Cancer
most people present with a palpable neck mass detected during a routine exam
Myxedema
occurs if hypothyroidism develops after growth; symptoms include a low metabolic rate, mental slowness, weight gain, and edema of the face and extremities, which often progress to coma and death
ADH (antidiuretic hormone)
or vasopressin, regulates free water resorption in the kidneys
Radioactive iodine is used to treat which types of thyroid cancer?
papillary and follicular
Thyroid function is regulated by what?
pituitary and hypothalamic hormones, which respond to complex systemic negative feedback mechanisms based on metabolic needs
Tumor extension beyond the sella turcica may cause what?
pressure or invasion into surrounding structures; these patients may experience headaches, diplopia, or other visual disturbances caused by the compression of the optic chiasm
Pituitary Tumor Treatment
primary goal is to normalize pituitary hormonal function or to relieve local compressive or destructive effects; surgery plays a significant role; Radiation therapy can be used if the patient is unfit for surgery or after surgery has been done
TSH (thyroid-stimulating hormone)
produced in the pituitary gland; causes direct stimulation of thyroid cells to produce and release hormones that are critical for carbohydrate and protein metabolism
The Medulla
produces epinephrine (adrenaline) under the regulation of the autonomic nervous system
Physiology of The Thyroid Gland
produces several hormones, including tri-iodothyronine (T3) and thyroxine (T4) which are responsible for metabolic regulation
What is the most common type of hypersecretory tumor?
prolactinoma; this tumor causes amenorrhea (absence of period), galactorrhea (discharge of milk when a woman is not pregnant or breastfeeding), and impotence in men
TSH secreting adenoma
rare; can result in hypothyroidism
MSH (melanocyte-stimulating hormone)
relates to skin pigmentation
Patients previously treated for thyroid cancer are typically monitored with what?
repeat radionuclide-based imaging
Acidophils
secrete GH and prolactin (PRL)
Basophils
secrete TSH, FSH, LH, MSH, and ACTH
Neurohypophysis
secretes oxytocin and ADH
Intrahypophyseal Pituitary Tumors
stay in the pituitary gland
FSH (follicle-stimulating hormone)
stimulates egg and sperm production
LH (luteinizing hormone)
stimulates other sexual and reproductive activity
What are the parts of the adrenal gland?
the cortex (outer portion) and medulla (inner portion)
Adrenal Gland Physiology
the cortex produces steroid hormones including glucocorticoids, mineralocorticoids, and sex hormones, which are responsible for metabolic regulation; these hormones include cortisol, aldosterone, estrogen, and androgen; the cells of these hormones are regulated by the ongoing stresses and needs of a person's metabolism
What can a CT scan show?
the local and regional extent of advanced or recurrent cancer
Papillary Cancers
the most common type of thyroid cancer; most frequently seen in people with previous irradiation; these are slow growing and non-aggressive and have an excellent prognosis; more common in females than males; peak incidence is third to fifth decade of life
What is the master regulatory gland?
the pituitary
The production of these hormones rely on what?
the thyroid glands ability to remove iodine from the blood
Pituitary tumors can also be classified according to what?
their growth patterns (by expansion or invasion) and are separated into intrahypophyseal, intrasellar, diffuse, and invasive adenomas
Adrenal Gland Anatomy
these glands are paired organs located on the superior pole of the kidneys; yellow cortex and dark brown medulla; lymphatic drainage is to the para-aortic nodes
How to detect to diagnose a functional pituitary tumor?
these tumors have characteristic endocrine abnormalities that are associated with the hyper-secretion of hormones; laboratory testing can directly measure hormone levels; the principal imaging study for pituitary gland is CT
What do each of the principal organs do?
they produce hormones under complex feedback-control mechanisms that affect various functions to meet ongoing metabolic needs and stresses of the organism
What are the principal organs of the endocrine system?
thyroid, pituitary, adrenal glands, endocrine portions of the pancreas, and parathyroid glands
Latent Period
time between exposure and incidence
What are some possible side effects of surgery for thyroid cancer?
tumor hemorrhage, damage to the parathyroid gland that results in temporary or permanent hypoparathyroidism, and temporary or permanent vocal cord paralysis
Stereotactic Radio-surgery
uses a high energy photon beam with multiple ports of entry convergent on target tissue
Adrenal Cortex Tumor Epidemiology
very rare with only 300 cases in U.S. per year; men and women affected equally although hyper-functioning is more common in women; tumors arise more commonly in the left gland; median age is 50 years
What is a syndrome associated with excess sex hormones?
virilization in women and feminization in men
When are radical neck dissections warranted?
when nodes are grossly involved with metastatic disease
Medullary Thyroid Cancer
1 to 4% of thyroid cancer; most appear spontaneously but the rest can occur as part of familial multiple endocrine neoplasia (MEN) syndromes; no gender differentiation; typically occur from the fifth decade on with spontaneous forms whereas familial forms have been seen under 10 and over 80; medullary has a worse prognosis than papillary and follicular
Pituitary Anatomy
1.3 cm in diameter; located at the base of the brain; attached to the hypothalamus by the infundibulum; lies in the sella turcica of the sphenoid bone; divided functionally and structurally into an anterior lobe (adenohypophysis) and a posterior lobe (neurohypophysis)
Follicular Cancers
12 to 17% of thyroid cancer; these have the greatest propensity to concentrate I-131; more common in women than men; average age is 50 to 58 years; has a worse prognosis than papillary
What is a syndrome associated with excess aldosterone?
Conn Syndrome (aldosteronism)
What is a syndrome associated with excess cortisol?
Cushing Syndrome
What are the four radio-pharmaceuticals most commonly used for radionuclide imaging of the thyroid?
I-131, I-125, I-123, and Tc-99m
Thyroid Cancer Etiology
Previous radiation therapy to the gland, especially as a child, is a huge risk factor
Goiter
a physical sign of an enlarged thyroid gland
Negative Feedback Loop
a sophisticated mechanism of stimulation and inhibition of endocrine organ function; it is critical for maintaining metabolic homeostasis (stability) and providing the organism with the ability to respond to various stresses
C cells
a specialized subgroup of cells within the thyroid; they produce calcitonin, which is a hormone involved in calcium metabolism
How are thyroid cancers staged?
according to the histologic type and the age of the patient
What are the glandular cells?
acidophils and basophils; these are responsible for the secretion of seven hormones
What is the third most common functioning pituitary tumor?
adrenocorticotrophic hormone (ACTH) secreting tumor; this results in an over secretion of cortisol which can cause Cushing syndrome or Nelson syndrome after adrenalectomy)
Most patients with medullary carcinoma initially have what?
an asymptomatic painless mass or with systemic symptoms of diarrhea related to vasoactive substances (calcitonin) produced by the tumor (this usually represents a late stage)
What will the laboratory testing involve?
analysis of the thyroglobulin and calcitonin levels; after surgery, elevated levels indicate residual, recurrent, or metastatic differentiated thyroid cancer; calcitonin levels that are elevated before surgery indicate C-cell hyperplasia or medullary thyroid cancer
Cretinism
appears in infants shortly after birth;it is a congenital condition characterized by dwarfism; symptoms include stunted growth, abnormal bone formation, retarded mental development, lack of muscle coordination, low body temp, and sluggishness
Adrenal Cortex Tumors
arise on the adrenal glands; rare; classified according to which portion of the gland from which they arise
Pituitary Epidemiology and Etiology
benign tumors that arise in the sella turcica; account for 10% of intracranial tumors; can be classified as functioning or non-functioning (as related to the hormones they produce); differ widely according to age, gender, and type of hormone secretion
What types of disorders disrupt the endocrine system?
benign, congenital, degenerative, traumatic, autoimmune, or infectious processes