Pulmonary aspergillosis in a horse with myelomonocytic leukemia

Acute myelomonocytic leukemia was diagnosed in a 2-year-old Standardbred mare that had hind limb edema and fever unresponsive to antibiotics. The mare had anemia, thrombocytopenia, and leukocytosis, with circulating myeloblasts and monocytoid cells. A bone marrow specimen was hypercellular, with myeloblasts and monocytoid cells. Peroxidase, chloroacetate esterase, and alpha naphthyl acetate esterase activities were detected in many bone marrow cells. Interstitial pulmonary densities were seen radiographically. The mare was euthanatized and necropsied. Infiltrates of leukemic cells were found microscopically in specimens of spleen, lymph nodes, liver, kidneys, gastrointestinal tract, and lungs. Granulomas containing fungal hyphae were seen microscopically in the lungs, and Aspergillus sp was isolated from the lesions.     

Acute myelomonocytic leukemia in a dog

Cytochemical stains and morphologic characteristics were essential in making the correct diagnosis in a dog with acute myelomonocytic leukemia, which initially was diagnosed as lymphoblastic leukemia. Response to a treatment regimen of cytosine arabinoside, thioguanine, vincristine, and doxorubicin, besides accomplishing complete remission, helped revise the initial diagnosis to acute myelomonocytic leukemia. After remission was achieved, the dog died of a fulminating viral infection.     

Acute myelomonocytic leukemia manifested as myelophthisic anemia in a dog.

A 10-year-old, Golden Retriever-type castrated male dog was found to have a hemogram consistent with myelophthisic anemia. Within 30 days the hemogram changed in such a manner that a myeloproliferative disorder was evident. On the basis of hematologic, cytochemical, and cytologic findings, acute myelomonocytic leukemia was diagnosed.     

Acute myelomonocytic leukemia with neurologic manifestations in the dog

A dog was presented with mandibular paralysis, photophobia, and diffuse atrophy of the cranial skeletal muscles. Physical examination also revealed glossal paralysis, reduction of the swallowing reflex, reduction of the pupillary light response, and generalized lymphadenopathy. Cytologic and ultrastructural examinations of blood films, bone marrow, and lymph node aspirates were consistent with acute myelomonocytic leukemia. Post-mortem examination revealed extensive, multisystemic neoplastic infiltration with marked involvement of the central and peripheral nervous systems, especially the cranial and lumbar spinal nerves and associated ganglia. Neurologic manifestations are unusual in acute myelomonocytic leukemia in the dog.     

Chronic myelomonocytic leukemia in a cat

A 1-year-old spayed domestic short-haired cat was referred with anorexia and weight loss. Hematologic findings indicated nonregenerative anemia, severe neutropenia and monocytosis. The feline leukemia virus (FeLV) antigen test was positive reaction by enzyme-linked immunosorbent assay. Dysgranulopoiesis with slight increase in blast cells were observed in bone marrow smears. On the basis of blood and bone marrow findings, the cat was diagnosed as chronic myelomonocytic leukemia (CMMoL), which possibly corresponds to a kind of the subtypes in human myelodysplastic syndrome (MDS).     

Acute myelomonocytic leukemia negative for alpha-naphthyl acetate esterase stain in a Holstein cow

A 4-year, 7-month-old Holstein cow presented with anorexia. Physical examination revealed masses in the interscapular region and vagina. Blast cells were detected in the masses and peripheral blood by fine needle aspiration cytology and hematological examination. By bone marrow aspiration, blast cells constituted up to 24.2% of all nucleated cells, and 22% and 2% of non-erythroid cells stained positive for myeloperoxidase and alpha-naphthyl acetate esterase (ANAE), respectively. Pathological examination revealed the mass lesions consisted of a proliferation of tumor cells, which were positive for monocytic markers (HLA-DR and Iba-1). The cow was diagnosed with acute myelomonocytic leukemia (AMML). Even when tumor cells are ANAE-negative, AMML cannot be completely ruled out and should be considered when diagnosing cattle with leukemia/lymphoma.     

Acute myelomonocytic leukemia (AML-M4) in a dog with the extradural lesion

A two-year-old dog having presented with neurological signs showed marked leukocytosis and appearance of blast cells in the peripheral blood. Hematological and bone marrow examination showed an increase in blasts having both myeloid and monocytic cells characteristics. The dog was diagnosed with acute myelomonocytic leukemia (AML-M4) on the basis of bone marrow findings. Although the dog was treated with a multi-combination chemotherapy, the neurological abnormalities progressed and the dog was euthanized. Myelographic examination and necropsy revealed the extradural lesion formed by AML-M4 around the cervical spinal cord and this lesion was considered as a cause of the neurological signs.     

Monocytic leukemia in a horse

On clinical examination, a six-year-old Hassian gray gelding with a history of impaired performance, slight cough, colic, and edema of the ventral abdomen, prepuce and the legs had reduced skin turgor, pale mucous membranes, forced costoabdominal breathing, reduced venous return, enlarged lymph nodes, and splenomegaly. Hematologic findings revealed anemia, leukocytosis and a high percentage of monocytoid leukemic cells. Generalized lymphadenopathy, splenomegaly, ascites, hydrothorax, and a diffusely thickened gut wall were found at necropsy. Massive infiltration with monocytoid leukemic cells was detected in lymph nodes, spleen, bone marrow, liver, gut wall, kidneys, and choroid plexus. Incubation of living cells obtained from a leukocyte concentrate with latex particles revealed phagocytosis in the leukemic cells on light and electron microscopy. The leukemic cells also had a marked alpha-naphthyl-acetate and naphthol-AS-acetate esterase activity, but were only weakly positive to naphthol-AS-D-chloroacetate esterase. A very weak alkaline phosphatase activity only was demonstrated in a few leukemic cells. On scanning electron microscopy, the leukemic cells had prominent ruffles and ridge-like profiles. These features of the leukemic cells excluded lymphocytic and granulocytic leukemia, and monocytic leukemia was diagnosed.     

Myelodysplastic changes in a cat with myelomonocytic leukemia

Submandibular and/or disseminated zygomycosis (mucormycosis) was diagnosed in 3 feeder pigs from 2 farrow-to-finish farms. Affected pigs were stunted and unthrifty. Each pig had a large unilateral submandibular granuloma replacing the mandibular lymph node on the affected side. Two pigs had disseminated lesions. One had an abscess on the serosa of the stomach; another had abscesses scattered throughout the liver and mesenteric lymph nodes. Impression smears were made of several masses and stained with blue-black ink. Examination of smears by light microscopy revealed coarse, infrequently septate, irregularly branching, mucoraceous fungi typical of a Zygomycete. Histologic examination of the submandibular masses revealed granulomas containing large numbers of mixed inflammatory cells, including giant cells. Mesenteric lymph nodes and liver abscesses had necrotic cores surrounded by fibrous capsules infiltrated by mixed inflammatory cells. Hyphae of a mucoraceous fungus were scattered throughout all masses. The 2 pigs submitted alive had marked serum hypoproteinemia, including hypoglobulinemia.     

Large granular lymphocyte leukemia in a horse

Large granular lymphocytes (LGL) occur as a leukemic or aleukemic neoplasia in humans,(1) rats,(2) cats,(3,4) dogs,(5) and horses.(6) The single case of equine LGL previously reported was aleukemic.(5) In contrast to this previous report of aleukemic equine LGL neoplasia, the leukemia in the case presented here established the antemortem diagnosis of LGL.     

Acute myelomonocytic leukaemia with short-term spontaneous remission in a cat

A 2-year-old, spayed female domestic shorthair cat was referred with a history of anorexia and depression of 1 week duration. On physical examination, the cat was lethargic and febrile, with splenomegaly, anisocoria and ulcerative stomatitis. A complete blood count (CBC) and a biochemistry profile showed leukocytosis, numerous blast cells in the peripheral blood, thrombocytopenia, hyperglobulinaemia and a positive test for feline leukaemia virus antigen. A diagnosis of acute myelomonocytic leukaemia was made on the basis of the results of bone marrow cytology, histopathology, and immunochemistry (CD3, CD79a, lysozyme, and myeloperoxidase) tests. Following an unexpected 1-month period of clinical and clinicopathological remission without chemotherapy, the cat relapsed and died 1 week later.     

A dog with acute myelomonocytic leukemia

A three-year-old dog with marked leukocytosis, lymphadenopathy, and diarrhea showed an increase in unidentified blasts in the peripheral blood, and they were proliferated in the bone marrow. The dog was diagnosed with myelomonocytic leukemia (M4) because the blast cells were demonstrated by cytochemical staining to be both myeloid and monocytic cells. Although the dog was treated with a multi-combination chemotherapy and induction therapy using vitamin K2, it died on day 47 after the first admission. This case is the first report of M4 in Japan.