Canine lymphoma Flashcards
What is lymphoma?
A diverse group of neoplasms that arise from the lymphoreticular cells (T or B cells).
Normally arises from lymphoid tissue but it can arise from virtually any tissue as lymphoid cells will be present
Which dogs are most affected by lymphoma?
IT CAN AFFECT VIRTUALLY EVERY DOG!!!
Most commonly:
- Middle age to old dogs.
- Gender – less common in entire females? Oestrogen protective effects
- Breed predispositions and familiar traits.
Name the 5 anatomical presentations of lymphoma - which is the most common
Multicentric (80%)
Craniomediastinal
Gastrointestinal
Cutaneous
Extra-nodal forms (CNS, renal, heart, bladder)
Describe the clinical presentation and signs of multicentric lymphoma in dogs
Generalized peripheral lymphadenopathy +/- other clinical signs.
- Some dogs clinically well
- Rapid deterioration
- Non-specific signs (weight loss, inappetence/anorexia, lethargy, pyrexia).
- More specific signs (diarrhoea, vomiting, cough, ocular signs)
- Regional oedema if lymph drainage impaired
Describe the clinical presentation and signs of cranial mediastinal lymphoma in dogs
- Can occur as solitary lesion or part of multicentric form
- Tachypnoea, dyspnoea.
- Signs of hypercalcaemia (T cell form)
- Occasionally pre-caval syndrome
- Altered position of PMI for cardiac auscultation, displacement of apex beat
What signs of hypercalcaemia may be seen in dogs with cranial mediastinal lymphoma
PU/PD, vomiting/diarrhoea, muscle tremors, anorexia, weight loss
What is pre-caval syndrome?
Impaired lymphatic drainage due to the mass location at the cranial mediastinum – ventral aspect of the neck is oedematous
List the clinical signs of GI (alimentary) lymphoma in dogs
- Vomiting, diarrhoea, weight loss, anorexia, pan-hypoproteinaemia (hypoalbuminemia), evidence of malabsorption.
- Abdominal masses or diffuse.
- Lymphadenopathy (abdominal and less commonly peripheral)
Describe the forms of cutaneous lymphoma in dogs
- Epitheliotrophic
- T cell
- Solitary or generalized - Non-epitheliotrophic
- More frequently B cell
- More likely to have lesions elsewhere
Describe the clinical signs and presentation of cutaneous lymphoma
Different appearances.
Progression to raised, erythematous plaques/nodules.
Variable pruritus
Describe extranodal hepatosplenic lymphoma
Aggressive, no peripheral lymphadenopathy
T cell
Describe extranodal CNS lymphoma
- Mass lesion or diffuse. Variable neurological deficits but commonly signs of multicentric or diffuse lesions.
- Commonly ocular involvement.
- Generally T cell
Define paraneoplastic syndrome
It is a syndrome (set of signs and symptoms) that it is a consequence of the tumour but it is not due to the presence of tumour cells in that location.
List some features of paraneoplastic syndromes
- Hypercalcaemia (PTHrp) – tumour produces a similar protein to PTH which increases the levels of calcium - mediastinal and GI forms
- Immune mediated diseases: IMHA, IMTP and Pemphigus foliaceous
- Monoclonal gammopathies (B-cell)
- Neuropathies
- Cachexia
Describe diagnosis of lymphoma
- In multicentric forms differential diagnosis = Infectious disease
- Variable in other forms.
- Diagnosis always cytology or histology
Describe histological grading of lymphoma
- Different classification systems. Overlap.
- Unclear significance of certain subtypes in terms of guiding treatment of prognosis
- Features with clinical or prognostic implications
- Grade (low, intermediate or high).
- Immunophenotype (B-cell, T-cell or null phenotype).
Describe the 5 stages of lymphoma
I = involvement limited to a single lymph node or single lymphoid tissue in a single organ
II = involvement of LNs in a regional area +/- tonsils
III = generalised lymph node involvement
IV = hepatic and/or splenic involvement
V = manifestations in the blood and involvement of bone marrow and/or organ systems
Describe the haematology results seen for lymphoma
Thrombocytopenia: 30 – 50%
Neutrophilia: 25 – 40 %
Lymphocytosis: 20%
Abnormal cells on smear
Describe the MST is dogs with lymphoma arent treated?
MST 4 – 6 weeks for asymptomatic dogs.
Consider euthanasia on symptomatic dogs.
Describe prednisolone alone therapy for lymphoma
Response rate ~ 30%
Median response duration 1 – 2 months.
More likely to make the patient resistance to chemotherapy
What is the gold standard for lymphoma treatment?
Multidrug chemotherapy
Describe multidrug chemotherapy for lymphoma
- Survival time varies depending on protocol and individual response.
- Lower doses of drugs and prolonger interval between doses compared to humans -> Less side effects.
- Rarely curative and very prolonged survivals in ~20% of cases.
Describe high dose COP therapy for lymphoma
- Prednisolone + vincristine + cyclophosphamide
- Well tolerated protocol
- Easily and safely administered in general practice setting
- Hematology performed prior to each treatment
- Urine sample prior to each cyclophosphamide
- Overall response rate 60 % – 80 %
- Median survival around 6 – 9 months
Describe discontinuous CHOP/CEOP therapy for lymphoma
- Prednisolone + vincristine + cyclophosphamide + doxorubicin or epirubicin
- Response rate 90 – 95%
- Median survival time 10 – 12 months
- No advantage to continuous treatment
- Same drugs as COP with Doxorubicin or Epirubicin added
- Much stronger protocol
