Lecture 14 2/25/25 Flashcards
What are the characteristics of feline LSA incidence?
-one of the most common feline cancers
-true annual incidence is unknown
-most common anatomic location is GI
How have vaccination protocols changed the presentation of feline LSA cases?
-reduced the percentage of patients that are concurrently FeLV+
-significantly raised the age of feline LSA patients
-changed the primary anatomic location from mediastinal to gastrointestinal
What are the characteristics of FeLV and FIV as risk factors for feline LSA?
-FeLV plays a direct role in tumorigenesis
-FIV plays an indirect role in tumorigenesis by causing chronic immunosuppression
-cats positive for both FeLV and FIV have an 80-fold increase in risk
-FIV+ only has a 5-fold increase in risk
What are the risk factors for feline LSA besides FeLV and FIV?
-environmental/second-hand smoke
-immunologic/renal transplants
-inflammatory/IBD
What are the classifications for feline LSA?
-anatomic location
-histologic grade
What are the anatomic locations for feline LSA?
-GI (most common)
-mediastinal
-nodal
-extranodal (renal, CNS, nasal)
What are the characteristics of GI LSA?
-most common form
-mainly in small intestine
-can be seen in stomach, ileocolic junction, and colon
-often diffuse rather than a focal mass
-more common in older, FeLV neg. cats
-differentials include IBD, FIP, and carcinoma
What are the characteristics of mediastinal LSA?
-10 to 20% of LSA cases
-mostly in young, FeLV+ cats
-can be seen in older, FeLV neg. siamese cats
-causes decreased thoracic compliance and dyspnea
-main differential is thymoma
What are the characteristics of nodal/multicentric LSA?
-not common; only 4 to 10% of cases
-causes peripheral lymphadenopathy
-can have spleen and liver infiltrates
What are the characteristics of renal LSA?
-1/3 of extranodal cases
-bilateral
-usually of primary renal origin but can be concurrent with GI LSA
-50% will develop CNS involvement
-main differential is polycystic kidney dz
What are the characteristics of CNS LSA?
-second most common CNS malignancy in cats
-overall rare dz
-can be intracranial, spinal, or both; both is very rare
-usually extradural
-primarily seen in younger cats; some are FeLV+
-80% have marrow involvement
-most difficult form to treat
What are the characteristics of nasal LSA?
-most common nasal tumor in cats
-most common form of extranodal LSA; next to renal
-occurs in older patients
-most are localized to nasal cavity but can see systemic involvement
-good prognosis with aggressive treatment
Which types of LSA are typically low grade vs high/intermediate grade?
low: GI LSA
-intermediate/high: all other types of feline LSA
When is cytology diagnostic for LSA in cats?
-effusions
-kidney
-liver
-focal GI mass
-non-lymphoid organs
What are the pros and cons of cytology for diagnosis?
pros:
-minimally invasive
-quick
-inexpensive
cons:
-not diagnostic for small cell GI LSA
What are the characteristics of biopsy as a diagnostic tool for feline LSA?
-used for small cell GI LSA
-best to get a full-thickness biopsy; cancer typically found in the muscularis
What are the pros and cons of biopsy for lymphoma diagnosis?
pros:
-best chance of diagnosing small cell GI LSA
cons:
-invasive
-requires GA
-more expensive
What are the challenges in diagnosing small cell GI LSA?
-histopath. is only 72% sensitive; difficult to distinguish LSA from IBD
-IHC is only 78% sensitive
-PARR has sensitivity of 83%, but clonal rearrangement can sometimes occur with inflammation and not cancer
Which tests are used for feline LSA staging?
-PE
-CBC/chem/lytes/UA
-FeLV/FIV testing
-thoracic rads
-abdominal ultrasound
-possible bone marrow aspirate
-possible CT/MRI
What are the characteristics of LSA staging via physical exam?
-cats are rarely asymptomatic, unlike dogs
-abnormalities relate to anatomic location
-GI location leads to weight loss, V+, D+
-can palpate intra-abdominal masses or thickened intestinal loops
-mediastinal location leads to dyspnea and decreased thoracic compliance
-peripheral lymphadenopathy is uncommon
What are the findings on CBC/chem that are of significance in staging?
-anemia; due to chronic dz, blood loss, or bone marrow abnormalities
-hypoproteinemia
-hypercalcemia (not super common)
What findings on thoracic rads are important for staging?
-pleural effusion
-mediastinal mass
-pulmonary infiltrates
What findings on abdominal ultrasound are important for staging?
GI:
-diffuse intestinal wall thickening
-GI mass
-mesenteric lymphadenopathy
-splenic/liver abnormalities
Renal:
-enlarged kidneys
Which tests may be indicated for further information when staging?
-bone marrow FNA (patients with pancytopenia)
-CT (nasal LSA)
-myelography/MRI/CSF tap (CNS LSA)
What are the treatment options for feline LSA?
-chemotherapy is mainstay
-radiation therapy for nasal lymphoma, CNS lymphoma, and/or localized lymphoma not responding to chemo
What chemotherapy combo is best for small cell LSA?
-chlorambucil and prednisolone
What chemotherapy combo is best for large cell LSA?
multi-drug protocol like CHOP; important that doxorubicin is included
What are the characteristics of prednisolone as a treatment for feline LSA?
-well tolerated
-no MDR-1 induction like in dogs
-must be cautious of diabetes
What are the characteristics of feline LSA prognosis?
with treatment:
-overall MST is usually shorter than dogs
-varies based on anatomic location and grades
without treatment:
-MST around 2 months
What is the 1/3 rule to treatment response in cats?
-1/3 of cats will survive the average amount of time
-1/3 of cats will respond well to treatment and outlive the average survival time
-1/3 of cats will respond poorly to treatment and not survive to the average survival time
What are the prognostic indicators for feline LSA?
-positive FeLV status is a neg. indicator
-small cell LSA is better than large cell
-nasal location has a better prognosis than all locations except GI
-aggressive treatment is a pos. indicator
-response to treatment is most important indicator
What is important about GI LSA prognosis?
small cell has an MST of 1.5+ years
What is important about mediastinal LSA prognosis?
FeLV neg. siamese cats have a better prognosis than FeLV cats with an MST of 12 to 18 months
What is important about nasal LSA prognosis?
MST of 1.5 to 2+ years
What is NOT prognostic for feline LSA?
-B cell vs T cell immunophenotype
-FIV status
-pre-treatment with steroids
