Feline Lymphoma Flashcards
describe the biological behavior of feline lymphoma
local: diffuse infiltration of the primary organs (wherever it is, it tends to be diffuse)
diffuse: considered systemic until proven others (via appropriate staging)
common feline cancer: very different from canine lymphoma!
what are general risk factors for feline lymphoma?
- FeLV+
- purebred: especially siamese
- chronically immunosuppressed
-post renal transplant
-FIV+ - environment: small increase in risk from secondary smoke
describe the 2 historical forms of feline lymphoma
pre FeLV vaccines:
-median age: 4-6 years
-mediastinal, nodal, and leukemias predominate
FeLV control era:
-median age: 11 years
-alimentary forms (esp low grade/small cell) predominate
-prognosis good
describe feline GI lymphoma
- most common feline GI cancer
-likely most common feline cancer overall - SI 4x more likely than LI
-jejunum/ileum mc sites - can also be in intestine +/- LNs, liver
- 2 subtypes
describe the 2 subtypes of feline GI lymphoma
small cell versus large cell
-T versus B cell equally aggressive in cats!
small cell:
-predominant grade: low
-mucosal depth of invasion
-behavior: less aggressive (indolent)
-immunophenotype: T cell (>90%)
-frequency: more common (3x, good news!)
-onset of clinical signs: chronic/months
-PE/imaging findings: diffusely thickened intestine
large cell:
-predominant grade: high
-transmural depth of invasion
-behavior: more aggressive
-immunophenotype: 50:50 B v. T cell
-frequency: less common
-onset of clinical signs: acute (days to weeks)
-PE/imaging findings: discrete mass more common
describe imaging of GI lymphoma
- abdominal x rays: less likely to be helpful
-unless obstruction, effusion, or mass effect - abdominal ultrasound: better diagnostic yield
-intestines: thickened bowel, loss of layering (diffuse versus focal), obstruction
-abdominal lymph nodes: enlarged in 33% or fewer of low grade
-peritoneal fluid
describe how to differentiate small cell GI lymphoma from inflammatory disease (IBD)
biochemical values and biomarkers: low reliability
imaging: inconsistent
cytology: low reliability
routine histology: 72% sensitive
IHC + routine histo: 78% sensitive
routine histopath/IHC/PARR: 83% sensitive
AKA: biopsy, IHC, and PCR are better differentiators!!
what biopsy sample do you submit for feline lymphoma diagnosis?
discrete mass (found on imaging)
-more commonly large cell (high grade) gives a cytologically high yield; lymphocytes look abnormal (aspirate alone can give diagnosis!)
diffusely thickened intestine:
-more commonly small cell (low grade) gives a cytologically low yield; lymphocytes look NORMAL, increased risk of false negative, biopsy is best!
compare and contrast endoscopic versus surgical biopsy
endoscopy:
-pros: less invasive, +/- shorter anesthesia, can view mucosal surface
-cons: SMALL, SUPERFICIAL samples, can’t reach whole GI tract, can’t see rest of abdomen
surgical:
-pros: full thickness samples, visualize entire abdomen, can biopsy other structures, including LNs
-cons: more invasive, can only view serosal surface
describe treatment/prognosis of GI feline lymphoma, large cell versus small cell
large cell:
-treatment: COP/CHOP (multiagent IV/oral chemo protocol, weekly or biweekly tx for approx 19-25 weeks), response rate is 30-40%
-prognosis: MST 6-9 months
small cell:
-treatment: chlorambucil (oral chemo given every other day to once every 2 weeks) + prenisolone, response rate is >90%
-prognosis: MST >18 months
describe mediastinal lymphoma
- thymus and/or mediastinal LNs affected
- median age: 2-4 years
- commonly develops in FeLV+ cats
- unique variant in young siamese cats
-potential for improved prognosis - general behavior
-aggressive
-poor response to chemo
describe clinical presentation of mediastinal lymphoma
- respiratory signs:
-tachypnea
-dyspnea
-cyanotic MM
-decreased lung sounds (pleural effusion) - weight loss
- +/- Horner’s syndrome, obstruction of cranial vena cava (caval syndrome)
describe diagnosis of mediastinal lymphoma
- chest rads:
-mediastinal mass
- +/- pleural effusion - cytology of mass or effusion:
-ultrasound guided FNA of mass is preferred (more direct way to get an answer than submitting cytology)
- +/- flow cytometry or PARR (esp if small cell); chylothorax versus lymphoma - abdominal ultrasound for staging
describe treatment and prognosis of mediastinal lymphoma
- CHOP or COP, response rates are low
- historical MST: 2-3 months
- improved prognosis for young cats or siamese
- possible improved prognosis for FeLV negative cats
describe feline nodal lymphoma
- MUCH less common in cats versus dogs
-4-10% of all feline LSA - historically linked with FeLV
- hodgkins-like lymphoma
-not recognized in dogs
-single node/chain of LNs
