title: Suspected myelodysplastic/myeloproliferative neoplasm in a feline leukemia virus-negative cat.
abstract: A 10-year-old castrated Domestic Short-Haired cat was presented to a primary care veterinarian for a wellness examination and laboratory examination for monitoring of diabetes mellitus. The CBC revealed marked thrombocytosis, leukopenia and macrocytic, normochromic anemia. The cat tested negative for FeLV and feline immunodeficiency virus, but was positive for Mycoplasma haemominutum by PCR. Hematologic abnormalities were not responsive to therapy, so a repeat CBC and a bone marrow aspiration for cytology were performed. Additional blood smear findings included anisocytosis with megaloblastic erythroid precursors, large platelets, eosinophilic myelocytes and metamyelocytes, and rare unidentified blasts. The bone marrow smear was highly cellular, and the cytologic pattern was consistent with myelodysplastic syndrome with an erythroid predominance. At that time, 15% blasts were present. The cat was treated with a vitamin K2analog, doxycycline, and prednisolone, but without a clinical response. Within 3 months, euthanasia was elected due to declining quality of life, and a necropsy was performed. Postmortem bone marrow smears were highly cellular and dominated by monomorphic blasts of unknown line of origin (52%), persistent marked erythroid and megakaryocytic dysplasia, and ineffective erythropoiesis and granulopoiesis. Immunohistochemical, immunocytochemical, and cytochemical stains resulted in a diagnosis of acute myeloid leukemia of unclassified type. Additional histologic findings included mixed hepatitis with trematode infestation and lymphoplasmacytic interstitial nephritis with fibrosis. The marked thrombocytosis with myelodysplastic syndrome and the FeLV-negative status of this cat were unusual. The difficulty in classifying the myelodysplasia and subsequent leukemia highlights a need for further reporting and characterization of these types of disease.
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Amy L
authors.identifier: http://orcid.org/0000-0002-3481-5393
authors.initials: AL
authors.lastname: Weeden
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Kyle R
authors.initials: KR
authors.lastname: Taylor
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Scott P
authors.initials: SP
authors.lastname: Terrell
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Gallagher
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
authors.forename: Heather L
authors.initials: HL
authors.lastname: Wamsley
mesh_terms: D000748:Anemia, Macrocytic / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000473:pathology; D001856:Bone Marrow Examination / Q000662:veterinary; D002371:Cat Diseases / Q000175:diagnosis* / Q000473:pathology; D002415:Cats; D048909:Diabetes Complications / Q000628:therapy / Q000662:veterinary; D004359:Drug Therapy, Combination / Q000662:veterinary; D007951:Leukemia, Myeloid / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D007970:Leukopenia / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D008297:Male; D009174:Mycoplasma / Q000235:genetics / Q000302:isolation & purification; D009190:Myelodysplastic Syndromes / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary; D054437:Myelodysplastic-Myeloproliferative Diseases / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D009196:Myeloproliferative Disorders / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary; D013922:Thrombocytosis / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*
keywords: Megaloblastosis; myelodysplastic syndromes; myeloid leukemia; myeloproliferative disorders; thrombocytosis