Case of mastocytemia and systemic mastocytosis in a dog: ProCyte Dx and Sysmex XT-2000i scattergram findings, morphologic features, and c-kit somatic mutation analysis.

A 10-year-old female Golden Retriever was presented for a recheck after the complete removal of low-grade complex mammary carcinoma. The in-house ProCyte Dx automated counts revealed moderate regenerative anemia and moderate eosinophilia. The ProCyte Dx WBC scattergram showed a cloud in an unusual place parallel and to the right of the monocyte dot plot location. Cells were classified as either monocytes or neutrophils with no clear separation. Complete blood count analysis performed in the laboratory on a Sysmex XT-2000iV analyzer showed moderate regenerative anemia and WBC count within RI; a differential count was not provided by the instrument. On the Sysmex XT-2000iV DIFF scattergram, neutrophil and eosinophil dot plots were present at the respective locations and appeared separated, but the instrument did not provide numerical results. In addition to the normal lymphocyte dot plot location, the second cloud of cells classified as lymphocytes was displayed to the right of the monocyte dot plot area. On the WBC/BASO scattergram, the second population of cells was present above and to the right of the leukocyte cluster. Morphologic assessment of the blood smear detected mastocytemia with 16% poorly granulated and degranulated mast cells. FNAs from the liver and spleen contained large aggregates of poorly granulated mast cells. C-kit somatic mutation screening detected the presence of point mutation S479I in exon 9 of the canine c-KIT gene. This is the first description of abnormal scattergrams from ProCyte Dx and Sysmex XT-2000iV analyzers in a dog with concurrent mastocytemia and systemic mastocytosis, and where cytologic assessments of a blood smear, liver, and spleen, and c-kit somatic mutation analysis were performed.