Feline Lymphoma Diagnosis and Treatment

Feline Lymphoma

• Feline lymphoma is a malignancy of lymphocytes, most commonly impacting lymphoreticular organs
• These include lymph nodes, spleen, and bone marrow
• The biological behavior is often local, with diffuse infiltration of primary organs
  • Distant spread is considered systemic until confirmed through staging
• Distinct from canine lymphoma in many ways
• Risk factors include FeLV+, purebred cats (especially Siamese), chronic immunosuppression, post-renal transplant, FIV+, and a slight increase from secondary smoke exposure

Lecture Objectives

• Predict feline lymphoma's likely biological behavior based on anatomical location
• Develop diagnostic and treatment plans for suspected feline lymphoma in various anatomical sites
• Compare diagnostic, treatment, and prognostic differences between large-cell and small-cell lymphoma of the feline gastrointestinal tract
• Identify general prognostic factors for feline lymphoma regardless of location

Feline GI Lymphoma

• Most common feline gastrointestinal cancer
• Jejunum and ileum are the most common affected areas
• Small cell lymphoma is 3x more frequent than large-cell lymphoma
  • Small cell subtype is generally less aggressive (indolent). This presentation typically has mucosal invasion, slower progression, and a longer onset of clinical symptoms.
  • Large cell subtype is more aggressive, with transmural invasion, rapid progression, and shorter onset of symptoms.
• Imaging like abdominal ultrasound (AUS) is more likely to show helpful diagnostic results for feline GI lymphoma versus abdominal x-ray (AXR)
  • AUS shows thickened bowel, loss of bowel layering (diffuse or focal), or bowel obstruction
  • In addition, enlarged abdominal lymph nodes (≤ 33% of low-grade cancers) and peritoneal fluid are possible indicators of the disease.
• Differentiating between inflammatory bowel disease and small-cell GI lymphoma can be difficult
  • Biochemical values, biomarkers, imaging, and cytology have low reliability
  • Routine histology and IHC + routines histology show 72% and 78% sensitivity, respectively; routine histopath/IHC/PARR is around 83% sensitive
• Taking a biopsy is recommended to ensure an accurate diagnosis over cytology

Temporal Changes in Feline Lymphoma

• Before FeLV vaccines, median age of feline lymphoma was 4-6 years, with mediastinal, nodal, and leukemia dominating
  • Prognosis was very poor
• After FeLV control era, median age was 11 years
  • Alimentary forms (esp. low-grade/small cell) are common, with better prognosis

Mediastinal Lymphoma

• Thymus and/or mediastinal lymph nodes are affected
• Commonly seen in FeLV+ cats, especially young Siamese cats
• Good potential for an improved prognosis
• Aggressive behavior and poor response to chemotherapy are common characteristics

Mediastinal Lymphoma: Clinical Presentation

• Respiratory signs include tachypnea, dyspnea, cyanotic mucous membranes, and decreased lung sounds (pleural effusion)
  • Weight loss and/or Horner's syndrome are also possible
  • Obstruction of the cranial vena cava (caval syndrome) might occur

Mediastinal Lymphoma: Diagnosis

• Chest radiographs may reveal a mediastinal mass, pleural effusions
• Cytology of any mass/effusion; ultrasound-guided FNA are preferred
• Flow cytometry or PARR can further aid diagnosis, particularly for small cell lymphoma
• Chylothorax vs. lymphoma requires analysis to determine
• Abdominal ultrasound (AUS) staging

Mediastinal Lymphoma: Tx + Px

• CHOP or COP treatment has low response rates
• Average survival time for historical Multiple System Treatment is 2-3 months
• Young Siamese cats and FeLV-negative cats may have improved prognoses

Feline Nodal Lymphoma

• Much less common than in dogs, accounting for around 4-10% of all feline lymphoma cases
• Historically associated with FeLV
• A subset may present as Hodgkins-like lymphoma
• Typically involves a single lymph node or lymph node chain
• Diagnosis often begins with fine-needle aspiration (FNA) and cytology, but may require flow cytometry, PARR, and/or histopathology to confirm a diagnosis, especially for Hodgkins-like lymphoma

Feline Nodal Lymphoma: Tx and Px

• Chemotherapy and localized treatment like surgery or radiotherapy are options based on the grade (high/low). High-grade (large cell) generally has a poor prognosis compared with low-grade (small cell), which has a far better prognosis.

Nasal Lymphoma

• Most common form of feline extra-nodal and non-GI lymphoma
• Typically localized to the nasal cavity in 80% of cases, with 20% having systemic spread
• Usually high-grade B-cell lymphoma
• It can frequently be confused with chronic rhinitis
• Often exhibits signs such as upper respiratory noises, discharge (including epistaxis), sneezing, hyporexia, weight loss, trouble sleeping, and discharge, upper respiratory noises, facial deformity, and decreased nasal airflow

Nasal Lymphoma: Signs and PE

• Clinical signs may include upper respiratory noises, discharge (including epistaxis), sneezing, hyporexia, weight loss, and trouble sleeping
• Physical exam findings may include discharge, upper respiratory noises, facial deformity, decreased nasal airflow, and potential inability to retropulse eyes

Nasal Lymphoma: Diagnosis

• Staging generally starts with abdominal ultrasound (AUS) and chest radiographs
• Additional diagnostic steps are skull CT scan (ideally with radiation therapy set-up).
• Biopsy is crucial to confirm diagnosis. Rhinoscopy-guided biopsies and aggressive nasal flushing are used to collect tissue samples from the nasal cavity, though cytology of nasal discharge yield low success.

Nasal Lymphoma: Tx and Px

• Radiation therapy is highly effective in treating solitary nasal lymphoma, which achieves a 75-95% response rate and allows clinical improvement within 1 to 2 weeks
• Median survival time is estimated at 1.5 to 3 years from the time of treatment
• Chemotherapeutic treatment is indicated if the lymphoma is disseminated or has spread beyond the nasal cavity; palliative radiation is also common for this disseminated type
• Palliative radiation is often used to improve nasal cavity signs (e.g., discharge)

Renal Lymphoma

• Characterized by azotemia (e.g., PU/PD, lethargy, hyporexia, weight loss) and enlarged kidneys with an irregular shape
• Associated with CNS involvement
• Diagnostic tools: abdominal X-rays (AXR) for bilateral renomegaly, abdominal ultrasound (AUS) for bilateral renomegaly, hypoechoic subcapsular thickening, and a “halo sign”; U/S guided renal FNA is the preferred method
• Poor prognosis

Renal Lymphoma: Diagnosis

• Treatment involves CHOP or COP chemotherapy protocols, usually with a 75% response rate
• Survival time is generally low, with median survival time between 3 and 7 months in the untreated patients

General Prognostic Factors for Feline LSA

• Factors such as response to treatment, tumor grade/size, substage (a versus b), FeLV status, and weight loss during treatment are considered crucial prognostic factors
• Factors such as B-cell versus T-cell, stage, and breed are not consistent indicators of prognosis

Ferret Lymphoma

• A relatively common malignancy in ferrets
• The disease usually mimics the pattern seen in felines, except for presenting in different sites
• Presentation often resembles cats and it is site-dependent. Patients exhibit a variety of symptoms, including generalized/nodal (asymptomatic), mediastinal (dyspnea, caval syndrome), gastrointestinal (weight loss, vomiting, diarrhea), and cutaneous (cutaneous lesions) signs
• Diagnosis may involve FNA/biopsies of affected lymph nodes and/or organs
• The prognosis and treatment options are generally similar to those for feline lymphomas

Ferret Lymphoma: Dx, Tx, and Px

• Full staging procedures
• CBC/Chem/UA
• CXR, AUS
• Chemotherapeutic protocols and site-specific (e.g., mediastinal) radiation therapy may be used as treatments; chemo protocol options mirror those used for feline patients, and the protocols are largely based on lesion site
• Prognosis in ferrets mirrors that in cats

Test your knowledge about the diagnosis and treatment of feline lymphoma. This quiz covers various imaging techniques, survival rates, and the efficacy of histopathology and immunohistochemistry in diagnosing inflammatory bowel disease. Challenge yourself with questions regarding clinical signs and treatment options.