Lecture 15 3/24/25 Flashcards by Danika Boltz

What are the most common GI tumors in dogs?

-primary GI lymphoma
-adenocarcinoma
-leiomyosarcoma and GIST

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What are the general characteristics of primary GI lymphoma in dogs?

-treated with CHOP chemo protocol
-poor prognosis

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What are the general characteristics of adenocarcinoma in dogs?

-most common in the large intestine and rectum
-high metastatic potential
-metastasizes to LNs, lungs, and peritoneum

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Why are leiomyosarcoma and GIST grouped together?

the histopathology of these two diseases looks identical and they can only be differentiated via immunohistochemistry

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Which tissue is affected by leiomyosarcoma?

smooth muscle

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What are the characteristics of GIST?

-affects interstitial cells of Cajal
-most commonly found in cecum
-commonly misclassified as leiomyosarcoma
-C-kit mutation present in nearly all cases

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Why is it important to differentiate leiomyosarcoma from GIST?

there are treatment options that vary based on the tumor type

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Where do leiomyosarcoma and GIST metastasize to?

-LNs
-liver
-mesentery

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What are the most common GI tumors in cats?

-lymphoma
-adenocarcinoma
-mast cell tumor

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What are the general characteristics of adenocarcinoma in cats?

-more common in small intestine than colon
-high metastatic potential

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What are the general characteristics of mast cell tumors in cats?

-GI tract is the most aggressive location for MCT
-high metastatic potential

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How are GI cancers diagnosed and staged?

-abdominal ultrasound plus FNA cytology
-exploratory laparotomy with histopath.
-minimum database
-thoracic rads

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When is surgery used as a treatment for GI cancer?

-cancers other than LSA
-no evidence of metastatic disease on staging

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When is chemotherapy used as a treatment for GI cancer?

GIST with metastasis

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What are the characteristics of GI cancer prognosis?

-prognosis is variable
-best prognosis for canine leiomyosarcoma/GIST with no metastasis and feline small cell GI LSA

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What are the four types of hepatobiliary tumors?

-hepatocellular (adenoma and carcinoma)
-bile duct (adenoma and carcinoma)
-mesenchymal (leiomyosarcoma, hemangiosarcoma, fibrosarcoma)
-neuroendocrine

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Which hepatobiliary tumor is most common in dogs?

hepatocellular carcinoma

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What are the possible distributions of hepatocellular carcinoma in dogs?

-massive
-nodular
-diffuse

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Which hepatobiliary tumor most common in cats?

biliary cystadenoma (benign)

What are the clinical signs of hepatobiliary tumors?

-may be asymptomatic
-lethargy
-anorexia
-weight loss
-vomiting
-icterus
-palpable mass(es)

How are hepatobiliary tumors diagnosed?

-abdominal ultrasound
-guided FNA
-biopsy and histopath.
-check clotting times prior to surgery

Why is guided FNA not typically diagnostic for hepatocellular carcinoma?

HCC is often well-differentiated and difficult to distinguish from adenoma

What finding is seen on CBC in hepatobiliary tumors?

anemia

What findings are seen on chem/lytes in hepatobiliary tumors?

-increased liver enzymes
-abnormal liver function parameters/GUAC
-paraneoplastic hypoglycemia

Which imaging modalities are used to stage hepatobiliary tumors?

-thoracic rads -CT of abdomen +/- thorax

What are the characteristics of surgery as a treatment of hepatobiliary tumors?

-best if tumor is confined to 1 or 2 liver lobes -good prognosis for dogs -excellent prognosis for cats; curative for benign tumors -hemorrhage is most common complication

What are the characteristics of non-resectable hepatobiliary tumors?

-approx. 9 month survival -no effective chemotherapy -palladia sometimes has some success

What are the characteristics of AGASACA in dogs?

-malignant tumor of the sweat glands in the anal sac -seen in middle to older aged dogs -can be unilateral of bilateral -moderate to high metastatic potential; goes to LNs and lungs -causes PTHrP-mediated hypercalcemia in 25% of patients

What are the clinical signs of AGASACA?

-swelling, bruising, and bleeding in the area -scooting -tenesmus/constipation -PU/PD if concurrent hypercalcemia -firm mass in area of anal sacs -enlarged sublumbar LNs

How is AGASACA diagnosed?

-FNA cytology -rule out infection

How is AGASACA staged?

-minimum database -thoracic rads -abdominal ultrasound -possible abdominal CT

What are the characteristics of surgery as a treatment for AGASACA?

-good option if there is no metastasis -want to remove primary tumor with clean margins -must leave > 50% of sphincter intact to preserve continence -dogs with larger tumors benefit from referral

What are the characteristics of surgical AGASACA treatment when the sublumbar LNs are involved?

-lymphadenectomy has been shown to benefit survival -may be associated with major complications -not all surgeons will remove sublumbar LNs; varies based on training and experience

What are the characteristics of definitive radiation as an AGASACA treatment?

-adjuvant to surgery if margins are incomplete -kills microscopic disease on the margins -4 week course -expensive -can lead to mucositis, proctitis, colitis, and diarrhea -improves survival by preventing local tumor regrowth

What are the characteristics of chemotherapy as an AGASACA treatment?

-adjuvant after surgery or surgery/RT -done when there is metastatic dz -no definitive survival benefit -some studies suggest improvement in survival -can use carboplatin, mitoxantrone, and melphalan

What are the options for AGASACA treatment if surgery is not an option?

-palliative radiation, esp. if patient is clinical -IV chemo/palladia -stool softeners -pain medication

What are the characteristics of AGASACA prognosis?

-good for small tumors treated with definitive surgery -early detection is key -guarded to poor prognosis for non-resectable and metastatic disease

What are the negative prognostic indicators for AGASACA?

-large primary tumor size -metastasis -no surgery for smaller masses -palliative chemo only

What are the characteristics of perianal tumors in dogs?

-adenomas are more common than adenocarcinomas -arise from sebaceous perianal glands -adenomas are testosterone driven and most common in male intact dogs -female and male neutered dogs should be checked for adrenal tumors

What are the characteristics of perianal adenocarcinomas?

-hormone-independent -more invasive -rapidly growing -moderate metastatic potential to LNs and lungs

What are the clinical signs of perianal tumors?

-one or multiple hairless perianal masses that may be ulcerated -possibility for pain -tenesmus possible

How are perianal tumors diagnosed?

-FNA cytology looking for "hepatoid" tumors -may need biopsy/histopath. for well differentiated adenocarcinomas

How are perianal adenocarcinomas staged?

-regional LN evaluation -thoracic rads -abdominal ultrasound

What are the treatment options for perianal adenomas?

-castration for male intact dogs -surgery -monitoring if slow-growing and/or significant co-morbidities

What are the treatment options for perianal adenocarcinomas?

-surgery with wide margins -possible radiation therapy -possible chemotherapy -NOT responsive to castration

What is the prognosis for perianal tumors?

-excellent with surgical removal for adenomas -variable for adenocarcinomas based on tumor size, presence of metastasis, and success of surgery