title: CD34+, CD41+ acute megakaryoblastic leukemia in a dog.
abstract: A clinically normal, 5-year-old intact female German Shepherd dog was presented to the local veterinarian to be spayed. Results of a preoperative CBC included mild nonregenerative anemia, severe thrombocytopenia, and 17% unclassified cells. On cytologic examination of aspirates from the dog's enlarged spleen and peripheral lymph nodes, a population of primitive round cells that occasionally resembled megakaryocytes was observed. A bone marrow aspirate specimen was markedly hypercellular with approximately 65% of marrow cells comprising a homogeneous population of immature hematopoietic cells similar to those found in the spleen, lymph nodes, and peripheral blood. Using immunocytochemical stains with canine-specific antibodies, all neoplastic cells strongly expressed cytoplasmic CD41 and 20-70% of the neoplastic cells expressed CD34 weakly to moderately. Rare (<0.5%) neoplastic cells weakly expressed vWF. The cells were negative for all other markers. Based on these results and the morphology of the neoplastic cells, a diagnosis of acute megakaryoblastic leukemia (AMegL) was made. In spite of treatment, results of a CBC performed 1 week later indicated progressive anemia and thrombocytopenia, and the dog was euthanized. To our knowledge, this report documents the first case of canine AMegL diagnosed with both anti-canine CD34 and CD41 antibodies.
authors.affiliation: Department of Veterinary Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA. steven_suter@ncsu.edu
authors.forename: Steven E
authors.initials: SE
authors.lastname: Suter
authors.forename: William
authors.initials: W
authors.lastname: Vernau
authors.forename: Michael M
authors.initials: MM
authors.lastname: Fry
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: London
mesh_terms: D000818:Animals; D000906:Antibodies / Q000097:blood / Q000302:isolation & purification; D018952:Antigens, CD34; D004283:Dog Diseases / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D004285:Dogs; D005260:Female; D007947:Leukemia, Megakaryoblastic, Acute / Q000175:diagnosis / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D040201:Platelet Membrane Glycoprotein IIb