B-cell lymphoma in a horse with associated Sézary-like cells in the peripheral blood.

This research article reports a case of B-cell lymphoma, a type of cancer, in a 22-year-old horse, where unusual forms of cells, similar to Sézary cells observed in human and canine cutaneous T-cell lymphomas, were found in the horse’s peripheral blood.

Case Background & Initial Examination

• The article begins with a presentation of the case: a 22-year-old Appaloosa gelding (a breed of horse) was brought in with a 2-week history of reduced appetite, lethargy, and swelling in the lower body. Over the days leading to its clinical consultation, the horse developed uneven skin nodules on the neck and side chest region. It was conscious, alert, and responsive at the time of the examination.
• The horse exhibited a rapid heart rate (tachycardia) and slightly fast panting (mild tachypnea). A light continuous murmur was detected during chest examination. The conjunctiva of its eyes was moderately swollen (chemosis), and the white part of the eye (sclera) showed mild yellowing. Significant swelling was also noted in its lower belly and external genitalia (prepuce).

Complete Blood Count (CBC) Observations

• In the complete blood count (CBC) results, there were several abnormalities including a normocytic, normochromic anemia characterized by a significantly reduced hematocrit and hemoglobin level. The mean cell hemoglobin concentration and mean cell volume were within an acceptable range.
• A sudden increase in the number of white blood cells (leukocytosis) and lymphocytes (lymphocytosis) was also observed. The lymphocytes in the peripheral blood were unusual, containing different looking cell populations, with many housing cerebriform nuclei, clustered chromatin, and limited basophilic cytoplasm. These cells were similar to Sézary cells seen in human and dog cutaneous T-cell lymphomas.

Additional Bloodwork Observations

• Other bloodwork results showed increased serum creatinine levels and significantly elevated total protein concentration. The concentration of globulin, a type of protein, was also notably high (hyperglobulinemia).
• Following these observations, a protein electrophoresis indicated monoclonal gammopathy of gamma 2 region, showing excessive concentration of a specific blood plasma protein. This protein was identified as immunoglobulin G through further immunoelectrophoresis testing, linking these findings to an immune response or a possible B-cell disorder.