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Guide to Lymphoid Neoplasia Testing

Which samples should be submitted when lymphoid neoplasia is suspected?

Which test should be submitted? The answer to this depends on the clinical signs, and the diagnostic question you are asking. In general, flow cytometry is preferred if it is possible to obtain a fresh sample. This is because flow cytometry can provide phenotypic information that PARR cannot. For example, if PARR demonstrates a clonally rearranged T cell receptor gene, that finding confirms neoplasia, but that neoplasm could be anything from an indolent T zone lymphoma to an acute lymphoblastic T cell lymphoma/leukemia. In rare cases, it could also be the result of a myeloid origin tumor.

One situation where PARR may be preferred is when only rare suspicious cells are noted in a sample. Even in these cases, it is usually best to try flow cytometry first, followed by PARR if the flow cytometry is inconclusive. PARR may be the only option to confirm neoplasia if a fresh sample cannot be obtained.

There are few antibodies for cats, and frequently both tests are needed to establish a diagnosis of neoplasia in feline patients.

Click on the link for each test to find out how to submit a sample. If cytology or histology give equivocal results, and/or you are seeking additional prognostic or diagnostic information, use the guidelines below to choose a test, or feel free to call the laboratory at (970) 491-1170 or email at

​ ​
Bes​t Test to Submit: 
Dog/Cat Lymphocytosis​ ​Peripheral Blood​ Small mature lymphocytes ​Flow Cytometry on
peripheral blood
Dog Lymphocytosis ​Peripheral Blood​ ​Immature forms/blasts  Flow Cytometry on peripheral blood​
Cat Lymphocytosis Peripheral Blood​ Immature forms/blasts  Flow Cytometry/ Immunotochemistry on peripheral blood​
​Dog/Cat ​Normal WBC ​Peripheral Blood​ Immature forms/blasts ​ Please call laboratory
Dog Lymphadenopathy​ ​Lymph node aspirate ​Any lymph node aspirate Flow Cytometry on fresh lymph node aspirate, follow up PARR may be necessary in some cases​.
Cat Lymphadenopathy​ Lymph node aspirate​ Confirmed or strongly suspicious of lymphoma Flow Cytometry on fresh lymph node aspirate​
Cat​ Lymphadenopathy ​Lymph node aspirate Homogeneous population
of small lymphocytes
Flow Cytometry on fresh lymph node aspirate
Cat Lymphadenopathy ​Lymph node aspirate Heterogeneous or reactive with rare suspcious cells PARR on lymph node aspirate ​
Dog/Cat Organomegaly​ Aspirate of organ​ Same rules as lymphadenopathy Same rules as lymphadenopathy​
Dog Cavity effusion ​Pleural/peritoneal fluid Large number of abnormal lymphoid cells/large number of small mature cells​ ​Flow Cytometry on a fresh sample of the effusion
Dog/Cat ​Mediastinal mass  ​Mediastinum Suspicious for either lymphoma or thymoma Flow Cytometry on a fresh aspirate from the mass is the best way to distinguish between these two entities.
​Cat ​Cavity effusion Plearal/peritoneal fluid​ ​Rare abnormal lymphoid cells PARR on cavity fluid ​
Elevated WBC consisting of normal or abnormal lymphocytes PARR on CSF (note that 50,000 nucleated cells are needed for a diagnostic PARR result)
Dog​ ​Leukopenia ​Bone Marrow  ​Blasts present ​Flow Cytometry on bone marrow in EDTA tube
Dog/Cat Leukopenia Bone Marrow  Small lymphocytes present ​Flow Cytometry on bone marrow​ in EDTA tube (peripheral blood is better if there is lymphocytosis)
Cat​ Leukopenia Bone Marrow  Blasts present ​Immunocytochemistry on bone marrow
Dog/Cat Leukopenia Bone Marrow  ​No clearly neoplastic cells  PARR on bone marrow​
Dog/Cat ​Hyperglobulinemia ​Serum ​Immunofixation on Serum
​​We cannot diagnose chronic myelogenous leukemia by flow or PARR​. ​If patient is female, an experimtental test may be applicable. Please call the lab.
​Testing blood or other
aspirates in cases
where the only sign is hypercalcemia is generally unrewarding. 
 Screening, no clinical signs 
​We do not recommend either PARR or Flow Cytometry to be used as a screening test in a healthy animal with no clinical signs.
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Contact Us:
​Clinical Immunology Laboratory
1619 Campus Delivery
Fort Collins CO 80523-1619​
This is a mailing address for correspondence, not the address for shipping samples. See submission form for sample shipping address.

​(970) 491-1170

​(970) 491-4242