Overview and Epidemiology
Lymphoma in cattle occurs in two principal forms:
- Enzootic Bovine Leukosis (EBL): Caused by bovine leukemia virus (BLV), affects cattle usually aged 4–8 years. Persistent infection, but only ~1–5% develop lymphosarcoma (vetmed.msstate.edu).
- Sporadic Bovine Lymphoma (SBL): Occurs independently of BLV, often juvenile (<6 months), thymic (<2 years), or cutaneous forms in young cattle (vetmed.msstate.edu).
EBL commonly manifests as multicentric lymphosarcoma, affecting lymph nodes, abomasum, heart, uterus, spinal cord, and other organs (vetspecialists.com).
Microscopic features of bovine lymphoma in the spinal cord. (A) Epidural mass, positive cytoplasmic staining of neoplastic lymphocytes. IHC for CD79α, bar = 100µm. (B) Diffuse large B-cell lymphoma, immunoblastic variant. Sheets of large cells with round, euchromatic nuclei. HE, bar = 100µm. (C) Diffuse large B-cell lymphoma, centroblastic variant. Sheets of large cells with highly variable nuclei ranging from round to indented (cleaved) and frequently with multiple nucleoli. HE, bar = 100µm. (D) Diffuse large B-cell lymphoma, anaplastic variant. Sheets of pleomorphic large cells with bizarre nuclear features. HE, bar = 100µm.
Clinical Signs
- Enlargement of superficial lymph nodes; internal organ signs vary per site (en.wikipedia.org).
- Systemic signs: weight loss, anorexia, poor milk yield, fever, lethargy (vetspecialists.com).
- Specific organ involvement:
- Cardiac: jugular distension, brisket edema, muffled heart sounds (dvm360.com).
- Abomasal: melena, anorexia, pyloric stenosis; ultrasound shows wall thickening and enlarged nodes (bmcvetres.biomedcentral.com).
- Spinal cord: hindlimb ataxia or paralysis in cases of epidural lymphoma (vetspecialists.com).
- Cutaneous: nodules/plaques on skin, often sporadic form (flockandherd.net.au).
Diagnostic Modalities
- Clinical exam: Palpation of external lymph nodes; rectal exam may detect internal masses .
- Ultrasound: Useful for detecting internal lymph node enlargement or abomasal wall thickening; fine-needle aspirates enable diagnosis (pubmed.ncbi.nlm.nih.gov).
- Histopathology and IHC: Confirms lymphoma type—B or T cell, diffuse large B cell histology common (vetmed.msstate.edu).
- BLV testing: Serology (ELISA/AGID) or PCR confirms viral infection (vetmed.tennessee.edu).
Image Interpretation
- Image 1 (turn0image0): Histopathological lymphoblast sheets and IHC confirming B‑cell phenotype.
- Image 2 (turn0image1): Cutaneous lymphoma nodules in a young heifer.
- Image 3 (turn0image2): External lymph node enlargement along ventral thorax indicative of thymic or multicentric form.
- Image 4 (turn0image3): High-power histology showing monomorphic lymphoid proliferation with abnormal mitoses.
Treatment and Prognosis
- There is no effective treatment; prognosis is grave. Affected animals should be humanely euthanized (flockandherd.net.au, vetmed.msstate.edu, vetspecialists.com).
- BLV control: test and segregate or cull positive animals; implement strict hygiene during blood-involving procedures (dehorning, injections) (en.wikipedia.org).
NAVLE‑Style Multiple‑Choice Questions
Q1: Diagnosis
A 5-year-old Holstein cow shows weight loss, peripheral lymphadenopathy, brisket edema, and muffled heart sounds. What is the most likely diagnosis?
A. Traumatic pericarditis
B. Bovine lymphoma (lymphosarcoma)
C. Right-sided heart failure
D. Abomasal ulcer
E. Sporadic juvenile lymphoma
Answer: B. Bovine lymphoma
Explanation: Lymph node enlargement plus cardiac signs suggest multicentric lymphosarcoma involving the heart (dvm360.com, dr.lib.iastate.edu, nadis.org.uk).
Q2: Diagnostic Approach
A cow has melena, anorexia, and thickened pyloric mucosa on ultrasound with enlarged caudal reticulum lymph nodes. What is the best next diagnostic step?
A. Trial NSAID therapy
B. Abdominocentesis
C. Ultrasound-guided fine-needle aspirate of the abomasum or lymph node
D. Treat for abomasal ulcer
E. Full-thickness abomasal biopsy via exploratory laparotomy
Answer: C. Ultrasound-guided fine-needle aspirate
Explanation: Minimally invasive aspirate + cytology/histology confirms lymphoma, avoiding unnecessary surgery (avmajournals.avma.org).
Q3: Risk Factor and Prevention
Which management practice is most effective at preventing EBL-related lymphosarcoma?
A. Routine vitamin supplementation
B. Frequent use of antibiotics
C. Testing and removing BLV-positive cattle, and avoid blood-contamination
D. Pasture renovation
E. Daily NSAID administration
Answer: C. Testing and removing BLV-positive cattle, and avoid blood-contamination
Explanation: BLV spreads via blood; control focuses on testing, segregation, culling, and hygiene during procedures (nadis.org.uk, vetmed.tennessee.edu).
References
- Merck Veterinary Manual – Bovine Leukosis (merckvetmanual.com)
- VetSpecialists.com – Bovine Leukemia and Lymphosarcoma (vetspecialists.com)
- BMC Vet Res – Ultrasonographic abomasal lymphoma findings (bmcvetres.biomedcentral.com)
- NADIS – Lymphatic and other Tumours in Cattle (nadis.org.uk)
- MSU Vet Med – Histopathology and epidemiology of bovine lymphoma (vetmed.msstate.edu)
- SagePub – Spinal cord lymphoma histology (journals.sagepub.com)