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27 Cards in this Set
- Front
- Back
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What is the incidence of skin tumors?
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most common tumors in dogs, 2nd most common in cats; more likely malignant in cat
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What type of cell can skin tumors be?
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can be epithelial, mesenchymal, melanocytic, or round cell
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What are the most common skin tumors of dogs?
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lipoma (benign), mast cell tumor (malignant), histiocytoma, perianal adenoma
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What are the most common skin tumors of cats?
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basal cell tumor, MCT, SCC, FSA
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How are skin tumors diagnosed?
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easily found, map tumor locations and measure, if you find it you should stick a needle in it
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What is the treatment for skin tumors?
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surgical excision is treatment of choice; chemo for some (based on: diagnosis, grade, presence of vascular/lymphatic invasion, overall patient health)
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What is the skin tumor that should not be excised?
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histocytoma (button tumor): tumor of young dogs, usually solitary, spontaneously regresses in 2-4 months
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What are the characteristics of mast cell tumors in dogs?
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can occur in any tissue, can occur in any location, may have waxing and waning history
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What do the cytoplasmic granules of mast cell tumors contain?
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histamine, heparin (blood clotting), chemotactic factors, platelet activation factor, proteases, kinins
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What is the signalment of mast cell tumors in dogs?
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middle aged, common breeds: boxers, labs, boston terriers, pug, beagle, weimaraner
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How do mast cell tumors present?
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small hairy mass or large ulcerated mass or large subcutaneous tumor or lymphadenomegaly
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How are mast cell tumors diagnosed?
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cytology (round cells, pink to dark purple granules, eosinophils often present); may need special stain; need **histopathology for grade
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What is the Patnaik grading system?
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grade 1 = low grade, benign; grade 2 = intermediate grade; grade 3 = high grade, malignant
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How are mast cell tumors staged?
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local, draining lymph node; skin metastasis is rare; thoracic radiographs; abdominal ultrasound; bone marrow aspirate
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What are the prognostic factors of mast cell tumors?
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grade: strongly predicts outcome; stage: lack of metastasis is better; **Mitotic index (<5 good, >5 poor prognosis - MST < 5months); location of tumor; presence of multiple tumors (not negative); breed; visceral, bone marrow, or GI is bad; growth rate (slow growing benign); c-kit mutation (high grade and aggressive); proliferation indices
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What is the treatment for MCT?
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H1 receptor antagonist: diphenhydramine; H2 blocker: famotidine, ranitidine, cimetidine; surgery, histopathology, DO NOT DEBULK; radiation therapy; chemo
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When should radiation be used for MCT?
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when surgery is not an option or incomplete margins; radiate 3 cm margin around surgical scar (5cm if possible)
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When is chemo used for MCT?
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chemo is used for metastatic dz (grade 3) or incomplete surgical excision --> vinblastine and pred most effective; lomustine less effective
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What is the cause of development of MCT in cats and dogs?
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Kit dysfunction (involved in signal transduction, growth regulation, cell differentiation)
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What is the MOA of tyrosine kinase inhibitors (TKI) for MCT?
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block the ATP binding site of RTKs (receptor tyrosine kinase) --> stops cell division and growth
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What are the veterinary TKIs? What do they inhibit?
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Mastinib; Toceranib;........ inhibit Kit, VEGFR, PDGFR and others (direct anti-tumor and anti-angiogenic activity
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When are TKIs used?
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high grade, high MI, non-resectable or recurrent (multiple tumors +/- metastasis)
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When should the use of TKIs be discontinued?
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discontinue before and after surgery (to keep from disrupting wound healing)
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What is the toxicity of TKIs?
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GI most common, neutropenia/ Toceranib: neutropenia, muscle cramping, hepatotoxicity; Mastinib: protein losing enteropathy, hemolytic anemia
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What cats are prone to develop Histiocytic MCT?
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young cats, siamese; spontaneously regress
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What cats are prone to develop Mastocytic MCT?
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older cats; small masses, diagnosed via cytology, reactive disease, surgery is tx of choice, histopathology needed
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What are common locations of visceral MCTs in cats?
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spleen, liver, intestines, stomach --> most common splenic dz in cats; need to remove the spleen
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