Onco 5 MCT

sihirlifil's version from 2018-05-01 20:58

Intro & Canine

Question Answer
List of round cell tumorsMCT
+/- malignant melanoma
+/- basal cell tumor
Where are mast cells derived from? how do they develop?Discrete round cells from BM precursor cells. Leave BM in immature state --> migrate to many tissues that have primary contact w/ foreign antigens (skin, respiratory & GI tract) --> mature into tissue mast cells --> help body respond to inflammation & allergies
Once mast cells are matured, what do they do in the body?Bind IgE on cell surface
Express receptors for complement components
Mediate inflammation: promote hypersensitivity reactions, stimulate T-cells, stimulate acute & chronic inflammatory responses
Activated --> release & production of various mediators: contents of granules (histamine, heparin, chondroitin sulfate, mast cell proteases, serotonin, proteolytic enzymes), lipid mediators (PG, leukotrienes, platelet activating factor), cytokines (TNF-alpha, IL-3, IL-4, IL-5, IL-6)
Mast cell mediators lead to what kind of reactions?Vascular permeability
Smooth muscle spasm
Bruising, edema
Activation of eosinophils & neutrophils
Histamine (undifferentiated) & heparin (well-differentiated)
Effects can lead to local hypersensitivity reactions, or systemic hypersensitivity (anaphylactic shock)
What is a MCT?Proliferation of mast cells
Is MCT common in dogs? cats?Most common cutaneous tumor in the dog
2nd most common cutaneous tumor in cat
Signalment of canine MCTMOST COMMON SKIN TUMOR! 7-21% of all skin tumors (11-27% of malignant)
Mean age 8-9y (range 3w-19y)
Breed: Boxers, pit bull, Boston terrier, Bulldog, lab & golden, beagle, Schnauzer
Behavior of canine MCTBenign to fatal depending on histology, grade, location, breed. “Predictably unpredictable”
Cutaneous MCT found where?(most common!) Trunk & perineum (50%), extremities (40%), head & neck
(Conjunctiva, nasopharynx, larynx, oral cavity, GIT)
Visceral MCT presents how?Almost always preceded by undifferentiated 1ry cutaneous lesion!
Lymphadenopathy, hepatosplenomegaly
Where does MCT metastasize?Regional LN 1st & most common
(Spleen, liver, BM)
How does MCT look?Vary in size, shape, appearance, texture, location (KJ sticks everything b/c you don’t know what you’re up against)
Most are solitary, 11-14% have multiple lesions
Etiology of MCTUnknown. chronic inflame, application of skin irritants, viral??? Genetic alterations (p53 alterations; p21 & p27 perturbations; c-kit expression)
CS of MCTAttributable to release of histamine, heparin, other vasoactive amines
Bruising, bleeding; Darier’s sign (erythema & wheal formation); gastric ulceration, V+, anorexia, melena, abdominal pain; waxing & waning tumor size
Why GI ulcers & anemia with MCT?Histamine release --> extra HCl
Diagnostics for MCTThorough PE
FNA! LN aspirate
Thoracic rads, abd US
+/- buffy coat smears (50% have circulating in buffy coat), BM aspirate
CT scan (approach to sx)
Why are rads/US done for MCT?Looking for big nodes! NOT PARENCHYMAL METASTASIS!
Wtf is this?
Special stain for MCT: AgNOR frequency (Argyrophyllic nucleolar organizing regions) (not usually done)
Higher count = worse KIT staining (C-kit is the receptor for stem cell factor, receptor mutation has been found in some canine MCT. Potential therapeutic target)
What is the Patnaik Grading System?Determines Tx & prognosis
What is the Bostock System?Pretty much same as Patnaik except reversed (i.e. grade III is good instaed of bad)
What is the Kuipel Grading System?2-tier Low & high grade system (more accurately predict biological behavior) (b/c every MCT was coming back grade II)
Characteristics of Grade I (Patnaik)Solitary
1-4cm diameter
Slow-growing, often present for months prior to presentation
Not usu ulcerated. Overlying hair may be lost
Characteristics of Grade III (Patnaik)Rapidly growing, ulcerated
Large in size, edematous & inflamed surrounding tissues
Cytology: Grade IWell-defined cytoplasmic borders, rare/absent mitotic figures, large numerous granules, regular spherical/ovoid nuclei, well-differentiated
Survival MCT CYTOLOGIC Grade I83% survived 4 years post-sx
Cytology: Grade IILower N:C ratio than anaplastic, infrequent mitotic figures, more granules, indistinct cell borders, cells closely packed, intermediate differentiation
Survival MCT CYTOLOGIC Grade II44% survive 4 years post-sx
Cytology: MCT Grade IIIHighly cellular, frequent mitotic figures, undifferentiated cytoplasmic boundaries, few granules, irregular size & shape of nuclei
Survival MCT CYTOLOGIC Grade III70% die/euthanized w/in 6 months of diagnosis
6% survive 4 years post-sx
Sites associated w/ poor prognosisTHOSE NOT ON AN EXTREMITY!
Prepuce, oral cavity, perineal, subungual, muzzle (higher metastatic rate?), other mucocutaneous
Why do aural MCT have poor prognosis?Higher grade, LN metastasis
Special about MCT in pugs?Tendency to get multiple MCTs
Special about MCT in BOXERS?Tend to get lower grade tumors!!! (& are most predisposed)… but may be at higher risk to develop additional MCT after sx removal
(WHO clinical staging)
General tx protocols (supportive)Hospitalize, IV fluids. NPO 48h
Famotidine (H2-antag), Diphenhydramine (H1-antag)
Omeprazole (PPI, prevents transport of H+ ions into stomach)
Metoclopramide (anti-emetic)
Chemotherapy protocolsPrednisone (steroid)
Vinblastine (vinca alkaloid)
What are the surgical margins?1cm for grade I, 2cm for II, 3cm for III
Get the DEEP margin!
Issues with surgery for e.g. elbow?Almost impossible to close, since need WIDE sx margins. High motion, friction
When is radiation therapy used?Solitary masses that were incompletely excised
Unresectable masses
Control rate for radiation therapyLocal: ~68%
Grades I & II >90% 3-yr
Survival MCT HISTOLOGIC Grade I100% at 12, 18, 24m (Sx resection)
Survival MCT HISTOLOGIC Grade II71% at 12m
56% at 18m
44% at 24m
(Median 500d)
Survival MCT HISTOLOGIC Grade III24% at 12m
19% at 18m
7% at 24m


Question Answer
Common in cats?2nd most common cutaneous tumor
More common to get visceral form than dogs
How is the grading system?Not prognostic!
Special about MCT in Siamese?May get spontaneously regressing MCT
Visceral forms: where? age?Spleen (50%). Mean age 10y
Intestinal (3rd most common 1ry intestinal tumor). Mean age 13y
10-15% of cats will have concurrent cutaneous MCT
What does feline MCT look like?Solitary firm, white-pink, raised, well-circumscribed, hairless, 0.5-3cm diameter mass (occasionally erythematous)
Most common sites of cutaneous feline MCTHead & neck, followed by trunk & limbs
**Visceral CS of feline MCTNSSSD (depression, anorexia, weight loss)
GI ulcers, D+, intermittent V+
Massive splenomegaly (feels like banana)
Dx of MCT(same as dogs) Thorough PE, min database (CBC/Chem/UA)
FNA, LN aspirate
Thoracic rads, abd US
+/- buffy coat smears, BM aspirate, CT scan (Cat-scan lolz)
TOC for feline cutaneous MCTSurgery
Behaviorally benign lesions, wide margins not critical, can be curative :)
Treatment options for feline MCTSurgery
Chemo??? (don’t respond as well)
Median survival w/ splenectomy1-2 years (cure?) Cats do well after splenectomy even with metastasis

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