For dogs, immunophenotyping by flow cytometry is almost always the test of choice because it can provide both a diagnosis and prognostic information. Flow cytometry can be more sensitive and less invasive than histology for detecting emerging lymphoid neoplasia. There are some forms of lymphoma, however, that require histology for subtyping and prognosis.
Cats more often have non‐neoplastic lymphocyte expansions in the blood and other organs, and fewer antibodies are available for immunophenotyping. In feline cases of lymphocytosis, flow cytometry of peripheral blood can sometimes provide prognostic information. In feline solid organs, however, PARR may be more useful for an affirmative diagnosis of lymphoma. A combination of histology and immunohistochemistry/PARR may be more useful than flow cytometry.
Guide to testing for hematopoietic malignancy
Use the guidelines below to choose a test. Some cases may require a combination of tests for definitive diagnosis and prognostic information. No diagnostic test can ever completely rule out cancer.
|Species||Clinical sign||Site||First test to submit||Notes|
|Dog||Cytologically suspicious or confirmed neoplastic lymphocytes in any tissue (solid organs, bone marrow, blood,|
|Affected organ||Flow cytometry||Do not submit blood when there is no lymphocytosis or cytologically suspicious cells in the blood.|
|Dog||Differentiating thymoma from lymphoma.||Mediastinum||Flow cytometry|
|Dog||Expanded population of lymphocytes in the peripheral blood that are cytologically normal.||Peripheral blood||Flow cytometry|
|Dog||Enlarged lymph nodes/spleen with lymphocytes described as cytologically normal.||Affected organ||Flow cytometry|
|Dog||Neurologic signs with significantly elevated white count in the CSF.||CSF||PARR||A minimum of 50,000 cells are needed for a diagnostic PARR result.|
|Dog||Flow cytometry results were equivocal.||PARR||Do not collect a new sample. PARR can be performed on the sample already submitted for flow cytometry.|
|Dog||Flow cytometry showed B cell chronic lymphocytic leukemia; looking for additional prognostic information.||Peripheral blood||Ki67||Ki67 expression indicates proliferation and is prognostic in B cell CLL.|
|Dog||Histologically suspicious cells in a lymphocyte-rich biopsy.||Request curls from the biopsy block.||PARR|
|Dog||Histology suspicious but not definitive for lymphoma.||Affected organ||PARR on the biopsy block or flow cytometry of a fresh aspirate.||In cases where a precursor neoplasm is suspected (acute leukemia, which can also present with primarily solid organ involvement) flow cytometry of a fresh aspirate is preferred.|
|Cat||Lymphocytosis||Peripheral blood||Flow cytometry||Flow cytometry can be diagnostic and prognostic, but many cases require follow-up PARR testing. If a myeloid, erythroid or acute leukemia is suspected, flow cytometry is not useful.|
|Cat||Cytologically confirmed neoplastic lymphocytes in any tissue.||Affected organ||Flow cytometry|
|Cat||Cytologically suspicious cells in any tissue or |
expansion of small lymphocytes.
|Cat||Equivocal evidence of neoplastic lymphocytes in a formalin‐fixed biopsy.||Request curls from the biopsy block.||PARR|
|Dog or Cat||Wanting to determine if plasma cells are neoplastic.||Any||PARR||We do not have antibodies to identify plasma cell by flow cytometry.|
|Dog or Cat||Suspicion for neutrophilic leukemia (CML) or eosinophilic leukemia.||Blood||None||We cannot distinguish neoplastic from reactive neutrophils or eosinophils by any currently available testing.|
Ready to submit a sample?
Additional Testing at CSU
Additional testing offered through the CSU Veterinary Diagnostic Laboratory may help with the diagnosis of a suspected hematopoietic disease.
|Complete blood count||CSU Veterinary Diagnostic Laboratories Test Information|
|Cytology||CSU Veterinary Diagnostic Laboratories Test Information|
|Protein electrophoresis and immunofixation||CSU Veterinary Diagnostic Laboratories Test Information|