Abstract
Acute monocytic leukaemia (M5a) was diagnosed in a 17-year-old Standardbred gelding with lethargy, intermittent pyrexia, oedema of the limbs, harsh lung sounds and submandibular lymphadeopathy. Haematological findings included moderately severe anaemia, thrombocytopenia and a leucocyte count within the reference interval, but characterised by neutropenia and numerous blast cells. Monocytic lineage of the cell population was suggested by examination of Wright-Leishman-stained blood and bone marrow smears. A panel of cytochemical stains disclosed diffuse cytoplasmic α-naphthyl-acetate esterase activity which could be markedly inhibited or abolished in all leukaemic cells by pretreatment with sodium fluoride. In ultrastructural preparations of buffy coat, neoplastic monoblasts had one to two nucleoli, dispersed chromatin, elongated mitochondria, scattered profiles of rough endoplasmic reticulum, bundles of microfilaments and pseudopodia. More differentiated monocytoid cells had infrequent lysosomal granules.
Similar content being viewed by others
References
Blue JT, Perdrizet J, Brown E (1987) Pulmonary aspergillosis in a horse with myelomonocytic leukemia. J Am Vet Med Assoc 190:1562–1564
Boudreaux MK, Blue JT, Durham SK et al. (1984) Intravascular leukostasis in a horse with myelomonocytic leukemia. Vet Pathol 21:544–546
Brumbaugh GW, Stitzel KA, Zinkl JG et al. (1982) Myelomonocytic myeloproliferative disease in a horse. J Am Vet Med Assoc 180:313–316
Bucchner-Maxwell V, Zhang C, Robertson J et al. (1994) Intravascular leukostasis and systemic aspergillosis in a horse with subleukemic acute myelomonocytic leukemia. J Vet Intern Med 8:258–263
Burkhardt E, v Saldern F, Huskamp B (1984) Monocytic leukemia in a horse. Vet Pathol 21: 394–398
Glick AD, Horn RG (1974) Identification of promonocytes and monocytoid precursors in acute leukemia of adults: Ultrastructure and cytochemical observations. Br J Haematol 26:395–403
Jain NC (ed) (1986) Schalm's veterinary hematology, 4th edn. Lea and Febiger, Philadelphia, pp 772, 890-895, 909-939
Jain NC, Blue JT, Grindem CB et al. (1991) Proposed criteria for classification of acute, myeloid leukemia in dogs and cats. Vet Clin Pathol 20:63–82
Latimer KS (1991) Leukocytic hematopoiesis and Diseases affecting leukocytes. In: Colahan PT, Mayhew IG, Merritt AM, Moore JN (eds) Equine medicine and surgery, 4th edn. American Veterinary Publications, Goleta, pp 1782–1783, 1815-1819
Latimer KS, Dykstra MJ (1984) Acute monocytic leukemia in a dog. J Am Vet Med Assoc 184:852–855
Lewis HB, Leitch M (1975) A case of granulocytic leukemia in the horse. Proc Int Symp Equine Hematol, Am Assoc Equine Pract 1:141–143
Mori T, Ishida T, Washizu T et al. (1991) Acute myelomonocytic leukaemia in a horse. Vet Pathol 28:344–346
Morris DD, Bloom JC, Roby KAW et al: (1984) Eosinophilic myeloproliferative disorder in a horse. J Am Vet Med Assoc 185:993–996
Searcy GP, Orr JP (1981) Chronic granulocytic leukemia in a horse. Can Vet J 22:148–151
Spier SJ, Madewell BR, Zinkl JG et al. (1986) Acute myelomonocytic leukemia in a horse. J Am Vet Med Assoc 188:861–863
Straub R, Tschidu P, Gerber H (1987) Akute monozytäre Leukämic beim Pferd. Pferdeheilkunde 3:251–253
Yam LT, Li CY, Crosby WH (1971) Cytochemical Identification of monocytes and granulocytes. Am J Clin Pathol 55:283–290
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Latimer, K.S., White, S.L. Acute monocytic leukaemia (M5a) in a horse. Comparative Haematology International 6, 111–114 (1996). https://doi.org/10.1007/BF00426052
Issue Date:
DOI: https://doi.org/10.1007/BF00426052