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cft ii > Exam 3 - Endocrine Tumors > Flashcards

Exam 3 - Endocrine Tumors Flashcards

1
Q

what dog breeds are predisposed to thyroid tumors? what are these tumors diagnosed as histopathologically?

A

boxers, beagles, goldens, huskies

90% of tumors SUBMITTED are carcinomas or adenocarcinomas

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2
Q

what is the median age of diagnosis for dogs with thyroid tumors?

A

9-11 years old

commonly diagnosed concurrently with other cancers

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3
Q

what is the most common origin of canine thyroid tumors? what are the subclassifications of this tumor type? are they usually functional?

A

follicular cell (thyroglobulin-producing) origin - further classified as follicular, compact (solid), papillary, or anaplastic

majority are non-functional in dogs

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4
Q

where do we commonly see ectopic thyroid tissue in dogs?

A

base of the tongue

hyoid apparatus

cranial mediastinum

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5
Q

T/F: in dogs with thyroid tumors, right & left lobes of the thyroid are affected with equal frequency with 67-75% being unilateral & 25-33% being bilateral

A

true

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6
Q

_________ (parafollicular/c cells that produce calcitonin) may have a less aggressive behavior than follicular cell thyroid tumors

A

medullary cell thyroid tumors

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7
Q

what are the common presenting signs of thyroid tumors in dogs?

A

clinical signs are due to the mass effect or invasion of the tumor into adjacent tissues

dysphagia, voice change, laryngeal paralysis, horner’s syndrome, & dyspnea

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8
Q

what are the common sites of metastasis for canine thyroid tumors?

A

locoregional lymph nodes, lungs, & abdominal organs

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9
Q

what is the metastatic potential for canine thyroid tumors?

A

35-40% will have metastatic disease at the time of diagnosis

up to 80% will develop metastasis

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10
Q

what is the gold standard for diagnosing/staging canine thyroid tumors?

A

histopathology!!!!

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11
Q

what do you need to consider when deciding on FNA vs. biopsy for a thyroid tumor in a dog?

A

THESE ARE VERY VASCULAR!!!! DO NOT BIOPSY!!!!!!

can use ultrasound guidance for FNA - need histopathology for gold standard diagnosis

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12
Q

what is the benefit of doing a CT for a dog with a thyroid tumor?

A

pre-surgical planning, look at local lymph nodes, & need to evaluate invasiveness & vascularity of the tumor

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13
Q

when would you do scintigraphy for a dog with a thyroid tumor? what information will it provide?

A

if you are concerned that it is a functional tumor

it will identify local residual disease present post-op, look for ectopic tumors, lymph node mets

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14
Q

what is a 99mtc-pertechnetate scan? what information does it provide?

A

part of scintigraphy that requires that a functional thyroid tumor is capable of trapping 99mTc with in the thyroid cells

may determine the likelihood of radioactive iodine treatment

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15
Q

what is included for clinical staging of canine thyroid tumors?

A

physical exam - palpate & measure tumor

cbc, chem, UA, T4, +/- blood pressure

FNA

thoracic rads

CT - head, neck, & thorax

+/- scintigraphy

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16
Q

why are invasive tumors not great for surgery for canine thyroid tumors?

A

less amenable to surgery due to invasion into surrounding structures including the trachea, esophagus, carotid artery, & recurrent laryngeal nerve

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17
Q

what is the benefit of using advanced imaging for canine thyroid tumors as far as determining prognosis?

A

determines if the mass remains encapsulated or if it is invading surrounding structures

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18
Q

is size a predictor of whether a thyroid tumor can be surgically removed?

A

nope!

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19
Q

what is the exception of poor prognosis in regards to a bilateral thyroid tumor in a dog?

A

bilateral, non-invasive thyroid carcinomas can be treated surgically!!!!

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20
Q

what are the prognostic factors in regards to size of the primary thyroid tumor in a dog?

A

<20 cm - 14% chance of metastasis, 21-100 cm3 - 74% metastasis, & > 100 cm3 - 100% metastasis

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21
Q

which is worse prognostically for canine thyroid tumors - unilateral or bilateral tumors?

A

bilateral is worse - 16x higher risk of metastasis

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22
Q

if you have a dog with a thyroid tumor that you have found to be metastatic after clinical staging, what are your treatment options?

A

palliative therapy - surgery, radiation, & chemo

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23
Q

if you have a dog with a mobile thyroid tumor with no metastatic disease after clinical staging, what are your treatment options?

A

surgical excision

chemotherapy - if tumor size is > 5 cm, vascular invasion is present, or you have a bilateral thyroid carcinoma

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24
Q

if you have a dog with a fixed thyroid tumor with no metastatic disease after clinical staging, what are your treatment options?

A

radiation therapy/radioactive iodine therapy

potential chemo - if tumor size is > 5 cm, vascular invasion is present, or you have a bilateral thyroid carcinoma

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25
Q

what is the risk of doing radioactive iodine therapy for treating an invasive, metastatic, or functional thyroid tumor in a dog?

A

not widely available & causes permanent bone marrow suppression

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26
Q

when may you do radiation therapy for local disease control for a dog with a thyroid tumor? what are the median survival times?

A

done for invasive tumors that are not amenable to surgery

hypofractionated - MST 5 to 20 months

definitive hyperfractionated - MST 24.5 months

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27
Q

what is the treatment of choice for canine thyroid tumors that don’t have extensive tissue invasion?

A

surgery is the treatment of choice!

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28
Q

what are the possible complications of surgical removal of a thyroid tumor in a dog?

A

hemorrhage, hypoparathyroidism, & laryngeal paralysis

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29
Q

what is the prognosis for surgical removal of a mobile, unilateral thyroid tumor in a dog?

A

excellent - MST >36 months, 70% 2 year survival rate

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30
Q

what should be done prior to surgical removal of a canine thyroid tumor because of its vascularity?

A

blood type the animal & have products on hand!

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31
Q

what is the most commonly used chemo in dogs with thyroid tumors?

A

carboplatin

32
Q

when may chemotherapy be considered for treatment of a dog with a thyroid tumor?

A

considered in dogs with large, non-resectable primary tumors and/or gross metastatic disease

33
Q

T/F: radiation therapy for dogs with fixed thyroid carcinomas have a good MST of 24-45 months after treatment which is better than an attempt at surgical removal

A

true

34
Q

what is the most common feline thyroid tumor in cats with hyperthyroidism?

A

multi-nodular adenomatous hyperplasia

35
Q

what is the least likely tumor cause of hyperthyroidism in cats? what therapy is recommended?

A

malignant thyroid carcinomas - highly metastatic, 70% to regional lymph nodes & lungs

surgical excision recommended!!

36
Q

T/F: 90% of dogs & cats have a single parathyroid mass

A

true

37
Q

what are the most common parathyroid tumors we see? what cells do they arise from? what does this cause?

A

adenomas - cystadenoma, adenocarcinoma, & hyperplasia

arise from the chief cells of the parathyroid gland which secrete PTH - leads to hypercalcemia

38
Q

what breed is predisposed to parathyroid tumors due to an autosomal dominant mode of inheritance?

A

keeshond

39
Q

how are parathyroid tumors diagnosed?

A

inappropriately high serum PTH in the presence of ionized hypercalcemia

73% will have PTH WNL, but normal PTH in the face of hypercalcemia is ABNORMAL

40
Q

what do you expect serum calcium, PTH, vitamin D, & phosphate levels to be in primary hyperparathyroidism?

A

calcium - increased

PTH - normal to increased

vitamin D - increased

phosphate - decreased

41
Q

what do you expect serum calcium, PTH, vitamin D, & phosphate levels to be in secondary hyperparathyroidism?

A

calcium - decreased to normal

PTH - increased

vitamin D - decreased

phosphate - increased or decreased

42
Q

what do you expect serum calcium, PTH, vitamin D, & phosphate levels to be in tertiary hyperparathyroidism?

A

calcium - increased

PTH - very increased

vitamin D - decreased

phosphate - increased

43
Q

how many parathyroid glands can you remove safely without risking permanent hypoparathyroidism?

A

you can remove 3 of the 4!!!!

44
Q

what is the long term prognosis for a patient after surgical removal of a parathyroid tumor?

A

excellent - about 10% experience recurrence

45
Q

what must be very carefully monitored in patients that have just had a surgical removal of a parathyroid tumor?

A

development of hypocalcemia!!!!

need to get them on oral calcium supplementation, calcitriol, & IV calcium if indicated

46
Q

what is the definitive therapy for parathyroid tumors?

A

removal of the hyperfunctioning glands - surgery is the treatment of choice

can also do ultrasound guided ablation

47
Q

what is the hallmark of insulinomas?

A

normal or increased blood insulin in the presence of low blood glucose!!!

48
Q

what are insulinomas?

A

tumor of the pancreatic beta cells that results in the excess secretion of insulin & other hormones (glucagon, somatostatin, GH, IGF-1)

49
Q

what is the most common cancer in middle aged to older ferrets?

A

insulinomas - 21-25%

50
Q

what are the clinical signs of insulinomas associated with?

A

signs are due to hypoglycemia!!!

dull mentation, star gazing, hind limb paresis, ptyalism, pawing at the mouth (ferrets), weakness, seizures, ataxia, & signs may be episodic

paraneoplastic peripheral neuropathy described in dogs

51
Q

what are your main differentials you should consider for hypoglycemia?

A

sepsis

severe hepatic disease - cirrhosis or a shunt

addison’s disease

idiopathic - juvenile, neonate, hunting dog

starvation

iatrogenic - insulin overdose

lab error

paraneoplastic - insulinoma, hepatocellular carcinoma, leiomyoma/leiomyosarcoma

52
Q

what is stage 1 metastasis of canine insulinomas?

A

only involves the pancreas

53
Q

what is stage 2 metastasis of canine insulinomas?

A

pancreas & lymph node involvement

54
Q

what is stage 3 metastasis of canine insulinomas?

A

distant mets

55
Q

T/F: documenting normal to elevated insulin levels in the face of hypoglycemia supports the diagnosis of an insulinoma

A

true

56
Q

what imaging may be used for diagnosing an insulinoma?

A

abdominal ultrasound - may be normal because many tumors can be super small, but still a good non-invasive test to look for the primary tumor & metastasis

dynamic CT or dual phase CT angiography may have a better sensitivity than ultrasound

57
Q

what is the treatment of choice for insulinomas?

A

surgery!!! surgical explore, partial pancreatectomy, & lymph node removal if possible

58
Q

what medical management is done for patients with insulinomas?

A

dextrose IV if an emergency situation!!!

prednisone - insulin antagonist that promotes gluconeogenesis & glycogenolysis

59
Q

T/F: for insulinomas, stage of the disease is prognostic

A

true

60
Q

what is the MST for dogs treated with surgery for an insulinoma?

A

758-1316 days!!!

61
Q

T/F: insulinomas are rare in cats

A

true - survival times range from 1 month to 32 months

62
Q

what are the 3 stages of disease for insulinomas in regards to prognosis?

A

stage 1 - 50% free of hypoglycemia 14 months post-op

stage 2-3 - <20% free of hypoglycemia 14 months post-op

stage 3 - metastasis developed at 6 months

63
Q

what is the mechanism of action of streptozotocin? why use it for insulinomas? what are the risks?

A

alkylating agent that is selectively taken up by GLUT-2 transporters

medical management of insulinomas

nephrotoxicity, hepatotoxicity, & DM in 42% of dogs

64
Q

what is the mechanism of action of diazoxide? why use it for insulinomas? what are the risks?

A

non-diuretic benzothiadiazine that suppresses insulin release from beta cells that 70% of dogs respond to & is fairly well tolerated

costly & limited availability

65
Q

what is the mechanism of action of octreotide? why use it for insulinomas? what are the risks?

A

somatostatin receptor ligand that inhibits insulin synthesis & secretion that alleviates hypoglycemia in about 50% of dogs

rare side effects but costly

66
Q

what is the mechanism of action of palladia (toceranib)? why use it for insulinomas? what are the risks?

A

small molecule inhibitor with an unknown mechanism

67
Q

what do gastrinomas cause?

A

secrete excessive amounts of gastrin - non-beta cell neuroendocrine tumor of the pancreas causing hypergastrinemia & gi ulceration

almost all reported in the pancreas

68
Q

why are gastrinomas so bad?

A

highly metastatic!!! identified in 85% of dogs & cats at the time of initial diagnosis

mets to liver, lymph nodes, spleen, peritoneum, small intestine, omentum

69
Q

what clinical signs are seen with gastrinomas?

A

signs associated with gastric acid hypersecretion & gastric mucosal hyperplasia

70
Q

what therapy may be used for gastrinomas?

A

cytoreductive surgery may help reduce secretory capacity of the tumor & enhance the efficacy of medical therapy

71
Q

what cells do glucagonomas arise from?

A

very rare - alpha cells in the pancreas

72
Q

what clinical signs are associated with glucagonomas?

A

necrolytic migratory erythema - hyperkeratosis, crusting, ulceration, erosions of the footpads, mucocutaneous junctions, external genitalia, pressure points, & ventral abdomen

73
Q

what other concurrent issues are often occurring with glucagonomas?

A

diabetes mellitus, hypoaminoacidemia, & increased liver enzyme activity

74
Q

how are glucagonomas treated?

A

surgical resection/cytoreductive surgery

metastasis at diagnosis is very common

75
Q

what cells do intestinal carcinoids arise from? what clinical signs are seen? what is the treatment of choice for these?

A

VERY RARE - arise from neuroendocrine cells arising from the gi tract, liver, gall bladder, & pancreas - clinical signs associated with location

surgical resection if possible

metastasis at diagnosis is very common

cft ii (28 decks)

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