Carryall, a 13-year-old, F/S DSH cat presented to specialty practice for lethargy, anorexia, and vomiting for 1 week. History provided to the clinical pathologist is as follows: HCT 15%, globulin 12.3, AUS showed possible round cell neoplasia in spleen. FNA of the spleen submitted.
The sample is highly cellular and in aggregates of cellularity, the population appears to be similar to the cells in the monolayer, representing a single population of cells with variable morphology. In normal canine and feline spleens, aspirates typically include aggregates of splenic stroma with surrounding lymphoid cells and hematopoietic precursors, creating the appearance of cellular heterogeneity, which is lacking in this sample. Very limited expected splenic elements are identified.
Plasma cell with expected nonneoplastic morphology. Low numbers may be present in normal spleens.
Metarubricyte, an expected hematopoietic precursor, and neoplastic plasma cell.
Plasma cell with cytoplasmic inclusions reminiscent of immunoglobulin (ie. Mott cell).
Abnormal mitotic figure, anisocytosis, anisokaryosis, multinucleation (criteria of malignancy).
Plasma cell neoplasia.
Why isn’t the interpretation multiple myeloma if there is also hyperglobulinemia (a criteria of multiple myeloma) noted in history?
Multiple myeloma implies bone marrow involvement, which may or may not be present in this patient. Plasma cell neoplasia has gotten a bit more complicated as a spectrum of manifestations is better understood and characterized across species. These vary from benign solitary plasmacytoma to multiple myeloma and myeloma-like conditions in dogs and humans. In cats, classification also includes extramedullary plasma cell neoplasia. While this variant in cats may not involve the bone marrow (extramedullary), extramedullary plasma cell neoplasia impacting organs, is also a malignant systemic disease that requires evaluation by an oncologist to best determine further diagnostic testing, treatment planning, and prognosis.
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