Lecture 20 4/4/25 Flashcards
What are the general characteristics of canine soft tissue sarcoma?
-common tumors of connective tissue
-seen in middle to older aged dogs
-no breed or sex predilection
-locally invasive with low-moderate metastatic potential
-arise from SQ tissues in any location
-appear pseudo-encapsulated, but are infiltrative
-local recurrence common is surgery is conservative
-metastasis via hematogenous route and primarily goes to lungs
-resistant to radiation and chemo
What are the histologic subtypes of canine soft tissue sarcoma?
-hemangiopericytoma
-peripheral nerve sheath tumor
-fibrosarcoma
-myxosarcoma
-liposarcoma
Which tumors are NOT included in canine soft tissue sarcoma?
-histiocytic
-synovial cell
-hemangiosarcoma
What are the histologic grades for canine STS?
-grade 1: low-intermediate, lower metastatic rate
-grade 2: low-intermediate, lower metastatic rate
-grade 3: high, higher metastatic rate
What are the clinical signs of canine STS?
-SQ mass that is fixed and soft to firm
-various history of onset
-painless
-possibly ulcerated and/or necrosed if large
How is canine STS diagnosed?
-FNA
-biopsy
What are the characteristics of canine STS biopsy?
-always incisional
-should be done away from the center and away from the normal/abnormal junction
-used for diagnosis only, not grading
What tests are used to stage canine STS?
-minimum database of CBC, chem/lytes, UA
-thoracic rads
-possible CT of tumor
What are the characteristics of surgical treatment for canine STS?
-margins should be 3 cm lateral and 1 fascial plane deep
-should submit whole specimen for histopath. for margins and grading
-second surgery if margins are incomplete AND anatomic location is favorable
What are the characteristics of definitive radiation therapy as treatment for canine STS?
-done for incompletely excised tumors that are not amenable to further resection
-expensive 4 week course of treatment
How does the grade of canine STS determine whether monitoring for recurrence following incomplete excision is acceptable rather than radiation?
-grade 1 has low recurrence rates (7-15%); monitoring is reasonable
-grade 2 has moderate recurrence rates (35-40%)
-grade three has high recurrence rates (>75%); radiation highly recommended
What are the characteristics of injectable chemo for canine STS treatment?
-use doxorubicin
-adjuvant for grade 3 tumors
-50% metastatic potential
-DOES NOT prevent local recurrence
-unclear if it delays/prevents metastasis
What are the characteristics of metronomic chemo for canine STS treatment?
-aimed at preventing tumor growth
-low side effect profile
-low dose oral med given at home
-relatively inexpensive if compounded
What is the prognosis for canine STS?
-excellent for low-intermediate grade with definitive treatment
-good to guarded for high grade
-guarded to poor for non-resectable tumors
-early detection and definitive treatment are best prognostic indicators
What are the risk factors for feline injection site sarcoma?
-vaccines; esp. adjuvant-containing (leading cause)
-long-acting glucocorticoids
-penicillin
-meloxicam
-deep surgical suture
-microchip
What is the etiology of FISS?
-inflammatory response + individual genetic variation = malignant transformation
-transition zone on histopath.
-growth factor overexpression
-mutation in p53 tumor suppressor gene
What are the physical exam findings in FISS?
-subcutaneous nodule(s) with cystic cavities
-firm, fixed nodules in areas of previous injections
What are the diagnostic options for FISS?
-FNA cytology
-incisional biopsy
Which tests are used for staging of FISS?
-minimum database
-thoracic rads
-T4 in older cats
Why is it important to do a CT or MRI scan for FISS?
-surgical planning
-radiation planning
What are the best prognostic indicators regarding FISS treatment?
-early
-aggressive
-multi-modal
What are the characteristics of surgery as a FISS treatment?
-must be aggressive
-lowest recurrence rates when margins are 5 cm lateral and 2 fascial planes deep
-margins of 3 cm lateral and 2 fascial planes deep will have high recurrence rates without radiation follow up
-surgery should be referred; time to recurrence is shorter if done in GP compared to boarded surgeon
-multiple excisions = poorer prognosis
What are the characteristics of radiation as a FISS treatment?
-adjuvant local therapy
-definitive
-significantly prolongs disease free interval
-includes an additional 3cm of margins
-must consider patient health, time, and financial constraints
-should begin therapy within 10-14 days of surgery; waiting longer decreases DFI time
-can still recur
-good 1, 2, and 3 year survival rates
What is the main side effect of radiation in cats treated for FISS?
leukotrichia
