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A 2‐month‐old cria that died following a short episode of constipation and diarrhoea was presented for a postmortem examination. The main macroscopic findings were widely disseminated, multinodular, whitish lesions involving liver and kidney and severe and diffuse haemorrhagic jejunitis. Histopathologically, the nodules are characterised by sheets of neoplastic round cells. An immunohistochemical panel including lymphoid, histiocytic/myeloid and pan‐neuroendocrine markers was performed. Taking into account the epidemiology of malignant round cell tumours in camelids, the neoplastic cell morphology as well as the negativity to all the tested markers, null cell lymphoma is considered as the most likely differential diagnosis. As recently highlighted by the literature, these findings confirm lymphoma as a potential systemic and aggressive neoplasm in young alpacas. [ABSTRACT FROM AUTHOR]

The article reports on the presence of gastric B-cell lymphoma with Mott cell differentiation in a crossbreed dog. Necropsy results show infiltrative masses in the duodenum, liver, and others are associated with lymph node enlargement. Results in cytology, and other tests show that the neoplastic cells were composed of B lymphocytes containing acid-Schiff-positive cytoplasmic globules suggest that the tumor is likely to be represented by a variant of B-cell neoplasia with Mott cell differentiation.

Background: Cyclophosphamide (CYP) and methotrexate (MTX) have been used as immunosuppressants in induction or maintenance protocols in a large variety of xenotransplantation models. Combining the use of transgenic porcine organs expressing human decay-accelerating factor (hDAF) with immunosuppressive therapy that included the use of CYP or MTX, survival of primate recipients of life-supporting renal xenografts has been prolonged. However, both drugs can cause significant systemic toxicity and, in particular, gastrointestinal (GI) toxicity. To date only limited data have been reported on the histopathological features deriving from the use of such agents in non-human primates. Methods: Cyclophosphamide or MTX was used as part of the immunosuppressive regimen in 15 bilaterally nephrectomized non-human primate ( Macaca fascicularis) recipients of a life-supporting hDAF porcine kidney. At post-mortem, a detailed analysis of the GI tract in animals receiving either CYP or MTX was performed. Paraffin-embedded sections of each portion of the GI tract were prepared and stained with hematoxylin and eosin (H&E). In some animals, additional investigations by immunohistochemistry (CD3, CD5, CD20, CD79 αcy, lambda, and kappa light chains) and by in situ hybridization for EBV encoded RNA (EBER) were undertaken. Results: The xenografted animals from the CYP group had a mean survival of 31 days (range: 0 to 90 days); animals from the MTX group survived a median of 14 days (range: 0 to 39 days). GI complications were the most frequent cause of euthanasia after renal failure. In CYP-treated animals GI-tract lesions were primarily characterized by diffuse, severe lymphoplasmocytic mucosal inflammatory infiltrate. Variable degrees of villi atrophy and fusion, gut-associated lymphoid tissue (GALT) and goblet cell hyperplasia were also observed. In MTX-treated primates, findings were consistent with severe villi atrophy associated with mild-to-moderate disseminated lymphoplasmocytic infiltration. Conclusions: In conclusion, GI tract lesions are an early and consistent finding when CYP or MTX are used as induction agents in this model. The two compounds induce different types of GI tract damage, however, in agreement with their different mechanisms of action. Whilst CYP primarily determines inflammatory lesions, MTX leads to a degenerative type of damage. This study indicates that immunosuppressive drugs can cause severe GI tract damage in primate recipients of renal xenografts and may be responsible for life-threatening lesions. [ABSTRACT FROM AUTHOR]