CD4 and CD8 double-negative immunophenotype of thymoma-associated lymphocytes in a dog. Academic Article uri icon

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.

published proceedings

  • J Vet Diagn Invest

altmetric score

  • 1

author list (cited authors)

  • Wikander, Y. M., Knights, K., Coffee, C., Vernau, W., Biller, D. S., Higginbotham, M. L., & Springer, N. L.

citation count

  • 3

complete list of authors

  • Wikander, Yvonne M||Knights, Kaori||Coffee, Calli||Vernau, William||Biller, David S||Higginbotham, Mary Lynn||Springer, Nora L

publication date

  • November 2020