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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

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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/Cat Lymphadenopathy​ ​Lymph node aspirate Confirmed or strongly suspicious of lymphoma Flow Cytometry on fresh lymph node aspirate​
Dog/Cat​ Lymphadenopathy ​Lymph node aspirate Homogeneous population of small lymphocytes Flow Cytometry on fresh lymph node aspirate
Dog/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/Cat 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
​Dog/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
​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