Feline Lymphoma: VetM5291 Lecture Notes (2025) PDF

Feline Lymphoma (a little bit about ferrets too ) Travis Laver, VMD PhD, DACVIM (Oncology) Assistant Professor of Oncology UGA College of Veterinary Medicine LECTURE OBJECTIVES After this lecture, you should be able to: Predict the most likely...

Feline Lymphoma (a little bit about ferrets too ) Travis Laver, VMD PhD, DACVIM (Oncology) Assistant Professor of Oncology UGA College of Veterinary Medicine LECTURE OBJECTIVES After this lecture, you should be able to: Predict the most likely biological behavior of feline lymphoma based on anatomic site Formulate a diagnostic and treatment plan for suspected feline lymphoma of different anatomic sites Compare diagnostic, treatment and prognostic differences between large cell and small cell lymphoma of the feline GI tract Identify general prognostic factors for feline lymphoma regardless of anatomic site General (cont.) Malignancy of lymphocytes Most commonly affects lymphoreticular organs: Lymph nodes Spleen Bone marrow https://upload.wikimedia.org/wikipedia General (cont.) Biological behavior Local: diffuse infiltration of the primary organ(s) Distant: considered systemic until proven otherwise (via appropriate staging) Common feline cancer In many ways very different from canine lymphoma! General Risk Factors FeLV+ Purebred: esp. Siamese Chronically immunosuppressed Post renal-transplant FIV+ Environment Small increase in risk from secondary smoke Temporal Changes in Feline Lymphoma FeLV era (pre-FeLV vaccines): Median age: 4-6 yo Mediastinal, nodal and leukemias predominate Prognosis very guarded FeLV control era: Median age 11 yo Alimentary forms (esp low grade/small cell) predominate Prognosis good Common Anatomic Presentations Alimentary Mediastinal Nodal Nasal Renal Other Feline GI Lymphoma Most common feline GI Cancer Likely most common feline cancer overall SI 4X more common than LI Jejunum/Ileum mc sites Intestine +/- LNs, liver  Feline GI Lymphoma Has 2 Subtypes Types Small Cell Large Cell Predominant Grade Low High Depth of invasion Mucosal Transmural Behavior Less aggressive (indolent) More aggressive Immunophenotype T-cell (>90%) 50:50 B v. T cell Frequency More common (3X) Less Common (1X) Onset of clinical signs Chronic (months) Acute (days to weeks) Diffusely thickened Discrete mass PE/imaging Findings intestine more common indolent – slowly progressive, usually over months to years Imaging of GI Lymphoma AXR: less likely to be helpful Unless obstruction, effusion or mass effect AUS: better diagnostic yield Intestines: Thickened bowel Loss of layering (diffuse v. focal) Obstruction Abdominal lymph nodes Enlarged in ≤ 33% of low grade Peritoneal fluid Diagnostic (& Philosophical?) Dilemma… Inflammatory Bowel Disease vs. Small Cell Lymphoma  TEST RELIABILITY Differentiating Biochemical values, Low biomarkers, etc… Small Cell GI Imaging Inconsistent Lymphoma From Cytology Low Inflammatory Routine Histo* IHC + routine histo* 72% sensitive 78% sensitive Disease Routine histopath/IHC/PARR* 83% sensitive Feline Lymphoma Diagnosis: What Sample? Discrete mass: More commonly large cell (high-grade) à cytology high yield Lymphocytes look abnormal Diffusely thickened intestine: More commonly small cell (low-grade) à cytology low yield Lymphocytes look normal Increased risk of false negative Biopsy is best  Biopsy Options Endoscopic Surgical Pros Pros Less invasive Full thickness samples +/- shorter anesthesia Visualize entire abdomen Can view mucosal surface Can biopsy other structures, (target biopsy) including LNs Cons Cons Small, superficial samples More invasive Can’t reach whole GI tract Can’t see rest of abdomen Can only view serosal surface Treatment/Prognosis – GI LSA (feline) Response Survival Treatment Rate (months) 6-9 Large Cell COP/CHOP* 30-40% (responders) Chlorambucil+ Small Cell >90% > 18 + Prednisolone *COP/CHOP – multiagent IV/oral chemotherapy protocols consisting of weekly to every other weekly treatments for ~19-25 weeks *Chlorambucil (leukeran) – oral chemotherapy given every other day to once every 2 weeks Mediastinal Lymphoma Thymus and/or mediastinal LNs affected Median age 2-4 yo Commonly develops in FeLV+ cats Unique variant in young, Siamese cats Potential for improved prognosis General behavior: Aggressive Poor response to chemo http://vet.tufts.edu/ Mediastinal Lymphoma: Clinical Presentation Respiratory signs Tachypnea Dyspnea Cyanotic mucous membranes Decreased lung sounds (pleural effusion) Weight loss +/- Horner’s syndrome Obstruction of the cranial vena cava (caval syndrome) Mediastinal Lymphoma: Diagnosis Chest radiographs Mediastinal mass +/- pleural effusion Cytology of mass or effusion Ultrasound guided FNA of mass preferred +/- flow cytometry or PARR (esp if small cell) Chylothorax v. Lymphoma AUS for staging Mediastinal Lymphoma: Tx + Px CHOP or COP Response rates low Historical MST = 2-3 months Improved px for young, Siamese Possibly improved px for FeLV-negative cats Feline Nodal Lymphoma MUCH less common in the cat (vs K9) 4-10% of all feline LSA Historically linked w/ FeLV Hodgkins-like lymphoma seen (see right) Not recognized in the K9 Single node/chain of LNs From Withrow and McEwen Small Animal Clinical Onc 5th ed Feline Nodal Lymphoma: Diagnosis Start w/ FNA and cytology Some cases will require more: Flow cytometry PARR (low sensitivity in cat) Histopathology – especially to diagnose Hodgkins like ** other anatomic forms may have LN involvement: complete staging (AUS, CXR) is usually indicated in cats with enlarged LNs diagnosed – rule out mediastinal mass, renal mass, etc… Feline Nodal Lymphoma: Tx and Px General Treatment Prognosis High Grade CHOP/COP Guarded (Large Cell) Fair (local Local Tx Hodgkins-like recurrence (surgery vs RT) common) Low Grade Chlorambucil + Very Good (Small Cell) Prednisolone Nasal Lymphoma Most common feline: Nasal tumor Form of extra-nodal, non-GI LSA Localization: 80% limited to nasal cavity 20% systemic Most are high grade B cell Chronic rhinitis v. neoplasia? Nasal Lymphoma: Signs and PE Clinical signs: Upper respiratory noise Discharge, including epistaxis Sneezing Hyporexia Weight loss Trouble sleeping PE findings Discharge Upper respiratory noise Facial deformity Decreased nasal airflow +/- inability to retropulse the eyes Nasal Lymphoma: Diagnosis AUS/CXR for staging 20% have extra-nasal disease Skull CT (ideally w/ RT set up) Biopsy Rhinoscopy guided Blind biopsy (know your landmarks, no brain bx! Aggressive nasal flushing (low yield) Cytology of nasal discharge (very low yield) Nasal Lymphoma: Tx and Px Solitary nasal Radiation therapy: 75-95% response rate Clinical improvement within 1-2 wks MST – 1.5-3 years Chemotherapy 75% response rate MST – 2 years reported (less in my experience) Palliative radiation therapy Disseminated (systemic) Chemotherapy Palliative radiation therapy to improve nasal signs Planning CT (pre-tx) Fraction 5 Fraction 10 Renal Lymphoma Signs primarily associated w azotemia: PU/PD, lethargy, hyporexia, weight loss PE: bilaterally enlarged irregular kidneys Linked with CNS involvement Diagnosis: AXR: bilateral renomegaly AUS: bilateral renomegaly Hypoechoic subcapsular thickening “halo sign” U/S guided renal FNA usually diagnostic Renal Lymphoma: Diagnosis Treatment: CHOP or COP 75% response rate Responses not durable MST 3-7 months From Withrow and McEwen Small Animal Clinical Oncology 5th ed General Prognostic Factors for Feline LSA (Regardless of anatomic site) Response to treatment Grade/Size Substage (a vs. b) FeLV status Weight loss during treatment NOT (at least not definitively) prognostic: B-cell v. T-cell Stage (conflicting reports) Breed https://www.bigstockphoto.com  Ferret Lymphoma 3rd most common ferret malignancy Insulinoma (#1) adrenal tumors (#2) Presentation: Site-dependent (like cats) Generalized/nodal - signs vary, possibly asymptomatic Mediastinal – dyspnea, caval syndrom GI/alimentary – weight loss, vomiting, diarrhea Cutaneous – cutaneous lesions Diagnosis: FNA or biopsy of affected LNs or organs Caution with enlarged abdominal LNs Chronic GI disease w/ lymphadenopathy (not neoplasia) common in older ferrets à potential for false-negative Small cell vs large cell forms They aren’t just small cats, BUT most of the same lymphoma principles apply Ferret Lymphoma: Dx, Tx and Px Similar to cat: Full staging indicated due to possible overlap of anatomic forms CBC/Chem/UA CXR AUS Other tests as indicated by the presentation Tx varies by site and type Chemo options very similar to cat Entirely oral protocols published to avoid repeated IV access RT based on anatomic form (eg mediastinal) Prognosis: In general, similar to cat Interested in exotics? Look for more on this from Dr. Mayer in the exotics course! CASE BLOODWORK