Bladder wall mass with neoplastic lymphoid cells in urine: diagnosis of secretory IgG B-cell lymphoma with Bence-Jones proteinuria in a dog

This article was originally published here

Veterinarian Clin Pathol. 2022 April 29. doi: 10.1111/vcp.13102. Online ahead of print.

ABSTRACT

In this study, we describe a multimodal approach to diagnose a single case of myeloma-related disease, extranodal B-cell secretory lymphoma with bladder involvement, monoclonal IgG4 gammopathy, and Bence-Jones proteinuria in a dog with a history 6 years of hyperglobulinemia that had not been further evaluated. A 12-year-old dog was presented for evaluation with a week-long history of tenesmus. Cytological evaluation of urinary sediment revealed low to moderate numbers of intermediate to large sized lymphocytes. We describe a technique that yielded sufficient numbers of viable neoplastic cells in urine sediment shipped for PARR and flow cytometry. These studies demonstrated clonal rearrangement of the immunoglobulin gene and expansion of CD21-positive and MHC class II-negative B cells, respectively. Protein electrophoresis with immunofixation and proteomic evaluation revealed serum and urine IgG4 monoclonal gammopathy with Bence-Jones proteinuria. MUM1 immunocytochemistry performed on urine sediment slides did not label neoplastic cells; thus, a plasma cell tumor was considered unlikely. Lack of response to chemotherapy based on cyclophosphamide, vincristine and prednisone led to euthanasia without autopsy 21 days after diagnosis. Lymphoma is the most common hematopoietic malignancy and accounts for up to a quarter of all neoplasms in dogs, but lymphoid neoplasms originating primarily from extranodal sites are rarely reported. Urinary tract neoplasia can be diagnosed by urine assessment in approximately one-third of canine cases, but the diagnosis of lymphoid neoplasia by urine assessment is rarely reported. This case highlights the usefulness of ancillary diagnostics on urine for the detection of lymphoid malignancies.

PMID:35488188 | DO I:10.1111/vcp.13102

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