Page 292 - ONLINE PROCEEDING BOOK WSAVA 2017
P. 292

An Urban Experience
WSVA7-0319
SURGICAL ONCOLOGY (VSSO)
MAST CELL TUMORS. MEDICAL AND SURGICAL APPRAOCHES
S. Ettinger1
1DR SUE CANCER VET PLLC, Oncology, TARRYTOWN, USA
MAST CELL TUMORS: MEDICAL AND SURGICAL APPROACHES
Sue Ettinger, DVM, DACVIM (Oncology)
Dr Sue Cancer Vet PLLC and Animal Specialty & Emergency Center Wappinger Falls, NY, USA
drsuecancervet@gmail.com
Biology and Etiology
Mast cells arise from bone marrow, are located in connective tissues throughout body, and are an important component of immune system. Mast cells play a central role in in ammatory and immediate allergic reactions. Mature mast cells store in ammatory mediators, including histamines, proteases, chemotactic factors, cytokines, and arachidonic acid metabolites. These may induce paraneoplastic syndromes in dogs with MCT
MCT Epidemiology & Risk Factors
MCT are the most common cutaneous tumor in dogs, accounting for 16 to 21% of skin tumors. Risk factors include
• Age: Higher incidence in older dogs (mean 9 y.o.) but also reported in young dogs
• Breed: Mixed breeds most common; Boxers, Boston Terriers, Labradors, beagles, schnauzers
• Gender Not correlated
MCT Etiology: The cause is largely unknown and they are rarely associated with chronic in ammation or application of skin irritants. There is no clear evidence of viral cause. The role of estrogen and progesterone are poorly de ned. Genetic alterations are also not completely understood, but the following have been associated: p53 - tumor suppressor, p21 and p27 - cell cycle regulation, c-KIT – RTK for stem cell factor
C-Kit is receptor tyrosine kinase (RTK) that binds to stem cell factor (SCF), the ligand. STF-kit interactions promote development of mast cells from hematopoietic progenitors. RTK are enzymes that transfer phosphate from ATP to cell protein and the phosphate is on the amino acid tyrosine. These are important in signal transduction and cellular activity, like cell division. Dysregulation in c-kit may promote mast cells’ uncontrolled growth or survival. 30-50% dogs with MCT
have c-kit mutations, essentially causing the cells to
be stuck in “on” position, leading to continuous c-kit activation and unregulated cell growth. The mutation is internal tandem duplications (ITD) in exons 11 &12 (in the juxtamembrane domain). ITD mutations associated with increased recurrence and death. Mutations have also been identi ed in exons 8 and 9.
Clinical Presentation
MCT are most common in dermal and SQ tissues. The sites are: Trunk 50-60%, Limbs 25%, and head & neck least common. They have a varied appearance. They are typically solitary, but 11-22% has multiple lesions.
The tumor clinical appearance is associated with histologic differentiation. Well-differentiated MCT are typically single, 1-4 cm diameter, slow growing, rubbery, non-ulcerated, alopecic, and present 6+ months. Undifferentiated MCT are large, rapidly growing, ulcerated and irritated, and the surrounding tissue is edematous and in amed. Small satellite nodules may be present
Disease symptoms can be complicate by signs attributable to release of histamine, heparin and other vasoactive amines. Darier’s sign refers to the wheal &  are in surrounding tissues following manipulation of the MCT and is caused by mast cell degranulation. GI ulceration causes vomiting possibly with blood, melena, anorexia, and abdominal pain. GI ulceration is due to histamine stimulation of H2 receptors on parietal cells that increased HCl. GI ulceration is noted in 35 to 83% necropsy specimens.
Prognostic factors
• Histologic grade
• Clinical stage
• Location
• Systemic signs
• Recurrence
• Tumor size
• Mitotic index (MI)
Diagnostics
Preliminary Diagnosis is typically made with  ne needle aspirate. On cytology, the neoplastic cells are small
to medium sized round cells, with abundant, small, uniform cytoplasmic granules that stain purplish-red (metachromatic)
To stage or not to stage? (or I’ve done my aspirate, now what) Should you do surgery  rst
OR diagnostics prior to surgery? Diagnostics may include incisional biopsy for grade, LN FNA, CBC, chemistry panel, UA,AUS +/- liver/spleen FNA, Bone marrow cytology, and buffy coat?
292
42ND WORLD SMALL ANIMAL VETERINARY ASSOCIATION CONGRESS AND FECAVA 23RD EUROCONGRESS


































































































   290   291   292   293   294