Page 40 - WSAVA2018
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 25-28 September, 2018 | Singapore
C. Cannon1
1University of Melbourne, U-Vet Animal Hospital, Melbourne, Australia
Claire Cannon BVSc (hons) DACVIM (Oncology) MANZCVS
University of Melbourne U-Vet Animal Hospital
Initial diagnosis
Cons: handling and shipping requirements may limit availability, as cells must be alive and in suspension.
· Newer biomarker tests (cRP, TK, haptoglobin) are available but their utility in routine clinical practice has not been demonstrated
Additional diagnostic tests: In my practice, I recommend additional diagnostic tests for a dog with known lymphoma if they alter prognosis, treatment options (what I would recommend or what the owner would choose to do), or there are abnormalities present that cannot be easily attributed to lymphoma.
· CBC, serum chemistry, urinalysis: Minimum
database required if chemotherapy is considered. Thrombocytopenia, lymphocytosis and neoplastic lymphocytes on blood smears in dogs with multicentric large cell lymphoma are associated
with bone marrow involvement (1, 2). Assess
for abnormalities that may require alterations in chemotherapy protocol (e.g. liver function in dogs to receive vinca alkaloids), be directly associated with lymphoma (e.g. hypercalcemia implying likely T cell immunophenotype in large cell lymphoma) or other concerns. Proteinuria is common in dogs with cancer, including lymphoma (3, 4), and may require ongoing monitoring, further investigation or intervention.
  · Fine needle aspiration (FNA) and cytology:
From peripheral lymph node, organ, blood/
bone marrow or other site. Pros: quick, non-
invasive. Immunocytochemistry may be done for immunophenotyping (T versus B cell). Definitive cytological diagnosis of lymphoma is reliable, however in situations where this is not possible additional diagnostics are required. Such situations include
small cell/low grade lymphoma, reactive lymph nodes, splenic location and non-diagnostic samples due to cell rupture or blood contamination. In the latter situation, adjustments in technique such as non-aspiration, smaller needle gauge, and using gentle techniques in making slides can improve diagnostic quality
· Staging:
1. Involving a single lymph node, or lymphoid tissue
· Biopsy and histopathology: Histopathology with immunohistochemistry (IHC) is gold standard for canine lymphoma diagnosis and subtyping. Excision
of a whole lymph node is recommended, but punch
or needle core biopsies may also be diagnostic. Histopathology is indicated when cytology is inconclusive, FNA is low yield (e.g. minimally thickened intestinal wall), or additional information about subtype is desirable. Pros: generally relatively quick turnaround time, (IHC may take longer). Can give significantly more information if performed by a pathologist experienced in lymphoma subtyping. Cons: More invasive and expensive than FNA and cytology.
2. Involvement of multiple lymph nodes in a regional area
3. Generalised lymph node involvement
4. Liver and/or spleen involvement (+/- stage III)
5. Blood, bone marrow and/or other systems
Each stage is subclassified into:
· Substage a: With systemic signs
· Substage b: Without systemic signs
In order to assign stage, full evaluation would involve, in addition to the minimum database, thoracic and abdominal imaging (usually chest radiographs and abdominal ultrasound) and sampling for cytology or histopathology, bone marrow evaluation and other evaluation depending on clinical presentation (e.g. MRI if neurological signs).
The prognostic impact of stage beyond stage III in dogs with multicentric lymphoma has not been fully defined. Certainly, involvement of liver and spleen does not seem to have a significant impact on prognosis, and bone marrow may or may not. Therefore, if complete staging does not significantly impact prognosis or treatment options, for many oncologists and owners, it is preferable to spend money on treatment rather than additional diagnostic tests. However, if there are specific localising signs e.g. vomiting, coughing, further evaluation may
be more warranted. As will be discussed later, large cell gastrointestinal (GI) lymphoma generally has a poorer prognosis and so identifying GI involvement may impact approach in cases with suggestive clinical signs.
· Immunophenotype: In large cell multicentric lymphoma, immunophenotype is one of the strongest
· PCR for antigen receptor rearrangement (PARR): Test for clonality, aim is to distinguish lymphoma from reactive lymphocyte population. Used where a definitive diagnosis of lymphoma cannot be made on cytology or histology alone. Pros: Can be performed on cytology
or histologic preparations, usually without the need for collection of additional samples. High specificity. Cons: Can be long turnaround time, often expensive, variable sensitivity (approximately 70-90%, can be affected by the tissue sampled and primers used). Best used for diagnosis rather than immunophenotyping of known lymphoma. Most commonly applied in suspected small cell GI lymphoma, in combination with histopathology and IHC.
· Flow cytometry: Assess cell surface markers using specific antibody stains. Pros: Superior to PARR for immunophenotyping, may be suggestive for diagnosis (cannot be used to definitively identify a clonal population), can diagnose some specific subtypes
(e.g. loss of CD45 in T-zone lymphoma), expression of additional proteins can be assessed (e.g. Ki67 or MHCII) which may have prognostic implications. Relatively non-invasive (fine needle aspiration), quick turnaround.
in a single organ (excluding bone marrow)

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