Peer-reviewed veterinary case report
Dog thymoma lymphocytes with unusual CD4 and CD8 markers
By Wikander, Yvonne M et al.·Published in Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc·2020·Department of Diagnostic Medicine/Pathobiology·View original on PubMed →
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Original publication title: CD4 and CD8 double-negative immunophenotype of thymoma-associated lymphocytes in a dog.
- Species:
- dog
Plain-English summary
A 10-year-old male dog with a mediastinal mass (a growth in the chest area) was found to have persistent small-cell lymphocytosis, which means he had an unusually high number of small lymphocytes in his blood. This condition can be linked to either thymoma (a tumor of the thymus gland) or small-cell lymphoma (a type of cancer). Tests showed that the dog's lymphocytes did not fit the typical patterns seen in thymomas, suggesting that there might be more variation in how these lymphocytes behave than previously thought. The findings highlight the importance of using multiple tests to accurately diagnose the condition, as relying solely on one type of test may lead to misdiagnosis.
People also search for: dog mediastinal mass symptoms · dog lymphocytosis treatment · thymoma in dogs diagnosis
Abstract
Persistent small-cell lymphocytosis in dogs with a concurrent mediastinal mass has been associated with both thymoma and small-cell lymphoma. In thymomas, neoplastic thymic epithelial cells induce overproduction and release of polyclonal lymphocytes, whereas thymic lymphoma results in thymic effacement by a clonal expansion of neoplastic lymphocytes and subsequent leukemic phase of lymphoma. Flow cytometry has been used to differentiate these 2 entities by immunophenotyping mediastinal mass aspirates. It has been reported that cases with mediastinal masses in which ≥ 10% of the associated small-cell lymphocytes were double positive for CD4 and CD8 were thymomas, whereas masses associated with < 10% were suggestive of lymphoma. We report a unique case of thymoma-associated lymphocytosis lacking the classic CD4+CD8+ immunophenotype. Our findings suggest that there may be more diversity in the thymoma-associated lymphocyte immunophenotype than has been identified previously; immunophenotyping alone might not be sufficient to differentiate thymic small-cell lymphoma from thymoma-associated lymphocytosis. In dogs with mediastinal masses and peripheral lymphocytosis, employing a variety of testing modalities to avoid misdiagnosis is prudent. These modalities include cytologic and/or histologic evaluation, immunophenotyping, and clonality assessment.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/32814519/