Acute B-cell lymphoblastic leukaemia in a 5-month-old boar.

CASE HISTORY: A 5-month-old mixed-breed boar presented with lethargy, weakness and anorexia of 1 week's duration. CLINICAL FINDINGS AND DIAGNOSIS: The boar had an elevated heart rate, slow capillary refill time and cyanotic skin over the ears; it was also severely anaemic. A necropsy revealed scattered petechial haemorrhages, small subcapsular white nodules on the kidneys, a nodule in the parenchyma of one testis, creamy-white bone marrow, a preputial diverticulum, and an ulcer of the pars oesophagea of the stomach. Cytology of peripheral blood and bone marrow identified large numbers of lymphoblasts, which were demonstrated using immunocytochemistry to be of B-cell origin. Histological examination of multiple organs also showed lymphoblastic infiltration. DIAGNOSIS: B-cell lymphoblastic leukaemia with secondary infiltration of lymphoid organs, kidneys, testis and preputial skin. CLINICAL RELEVANCE: This is the fi rst known reported case of acute B-cell lymphoblastic leukaemia in swine.

Acute B cell lymphoblastic leukaemia in a 12-week-old greyhound.

A 12-week-old greyhound had a two-day history of lethargy, inappetence and shifting lameness. Clinical examination revealed pyrexia and hepatosplenomegaly. Haematological examination showed anaemia, thrombocytopenla, neutropenla and large numbers of atypical mononuclear leucocytes. A diagnosis of acute B cell lymphoblastic leukaemia was made following flow cytometric immunophenotyping of the leucocytes. The owner declined further evaluation and the dog was treated symptomatically with antibiotics. After a brief improvement, the dog's condition deteriorated and it was euthanased four days after initial presentation. The case was unusual because acute lymphoid leukaemia in the dog is most frequently reported in mature animals. This is in contrast to humans, where acute leukaemia is one of the most common childhood cancers.

Latent Epstein-Barr virus infection in cottontop tamarins. A possible model for Epstein-Barr virus infection in humans.

The association of Epstein-Barr virus (EBV) with a growing number of human malignancies underlines the importance of efforts aimed at preventing the infection with this potential carcinogen and of establishing animal models for human virus-associated tumors. Cottontop tamarins have been used in EBV vaccine studies because virus infection regularly induces lymphomas similar to those seen in human immunocompromised individuals. In recent years, several vaccines based on the gp340/220 envelope protein of EBV have been developed and shown to prevent the development of EBV-associated lymphomas in this model. Using in situ hybridization and immunohistology, we have characterized EBV infection in one nonimmunized and three immunized animals after challenge with a standard tumorigenic dose of EBV. In the nonimmunized animal, EBV-infected lymphoid cells were detected in numerous tissues showing no obvious lymphoma infiltration. Surprisingly, variable numbers of virus-carrying cells were also found in all three immunized animals that were protected against the development of virus-associated lymphoma. This observation demonstrates that vaccination does not induce sterilizing immunity against EBV infection in this model. Double labeling suggested a B cell phenotype of the majority of these cells. EBV infection of nonlymphoid cells was not observed. Analysis of viral gene expression in immunized animals suggested a restricted form of virus latency different from that seen in EBV-driven lymphomas in nonimmunized cottontop tamarins. These results raise the possibility that immunized cottontop tamarins protected against the development of EBV-driven lymphoma or animals exposed to a sublymphomagenic dose of virus may serve as a model for EBV infection in humans.

Maxillo-orbital lymphoma (Burkitt's-type) in an infant Macaca fascicularis.

A 5-month-old male cynomolgus monkey (Macaca fascicularis) with facial deformation and proptosis of the left eye was euthanized due to a rapidly-growing peribulbar and retro-orbital mass. The mass invaded the soft tissue behind the right eye and extended ventro-medially through the lacrimal, ethmoid, maxillary and frontal bones. Caudo-dorsal extention of the mass through the left frontal bone and into the meninges and parenchyma of the frontal cerebral lobe was observed. Histologically, the cell population making up the mass was variable, but most of the neoplastic cells were blast-like with a large central round to ovoid nucleus, active coarsely stippled euchromatic chromatin, 1-4 prominent nucleoli and sparse cytoplasm. Interspersed between these neoplastic lymphocytes were numerous aberrant mitoses and histiocytes with foamy cytoplasm producing a "starry-sky" pattern. Cells further away from the central neoplastic core and closer to fragmented bone surfaces had plasmacytoid features with an eccentric hyperchromatic nucleus and abundant eosinophilic cytoplasm. Electron microscopy confirmed the formentioned cell types. Morphometric analysis of tumor cell indicated similarities to cells of human Burkitt's lymphoma. The tumor cells indicated similarities to cells of human Burkitt's lymphoma. The tumor was diagnosed as a malignant lymphoma of unknown etiology, similar to those seen in African children with Burkitt's lymphoma.

A spontaneous lymphoblastic lymphoma in a guinea-pig.

The exceptional carcinoresistance of guinea-pigs is well known and only a few cases of spontaneous leukaemia and several very rare cases of lymphoma have been reported in the literature. A spontaneous malignant tumor in an old male hybrid guinea-pig is described. The monomorphous aspect of the tumour, the cellular cohesiveness, the "starry-sky" pattern and the immunocytological characterization of tumour cells as B lymphocytes bearing IgM, lead to describe this tumour as a probable spontaneous Burkitt-type malignant lymphoblastic lymphoma.

Malignant lymphoma resembling Burkitt's tumour in rhesus monkeys: (light- and electron microscopic studies).

Spontaneous tumours of the haematopoetic system have been only rarely observed in nonhuman primates. We had the opportunity to carry out light and electron microscopic investigations of three lymphomas in immature rhesus monkeys from our colony. All animals had tumours of both retroperitoneum and lymph nodes. The relatively uniform lymphoblastic or lymphoreticular tumour cells as well as the massive occurence of the so-called "starry sky macrophages" were histologically characteristic. Histochemically, the marked pyroninophilia of these tumour cells was evident. The electron nicroscopy revealed the tumour cells as lymphoblasts of about 8 mu diameter with the following features: round or oval, occasionally deeply indented cell nuclei with relatively clear interchromatinic substance; mostly well developed nucleoli; sparsely, rough endoplasmatic reticulum; large numbers of free ribosomes and polyribosomes; a few large, bizzarre mitochondria, often situated at one pole; lipid vacuoles in some cells. These histological, cytological and electron microscopic characteristics correspond to those of the human Burkitt's Lymphoma. This tumour is classified as an undifferentiated malignant lymphoma. Tumours of this type are of particular interest on comparative and epidemiological reasons in light of the existence of morphologically similar experimental, virus induced lymphomas in monkeys.