Atypical form of sporadic bovine leukosis (SBL) in the Netherlands

Pathological findings and differential diagnoses of lymph node diseases in slaughtered cattle in Brazil: A study of 2000 samples

Slaughterhouse inspections play a crucial role in the sanitary control of zoonoses and foodborne diseases. This study aimed to identify and analyze the frequencies of lymph node diseases in cattle slaughtered for human consumption, using the samples sent to the anatomic pathology service of the Federal Laboratory for Agricultural Defense (Laboratório Federal de Defesa Agropecuária), Minas Gerais, Brazil, from January 2015 to September 2022. In total, 2000 lymph node samples were analyzed, and additional information was individually retrieved. Lesions were most frequently identified in thoracic lymph nodes. Bacterial isolation and quantitative polymerase chain reaction (qPCR) were performed using samples suspected of tuberculosis. Tuberculosis cases accounted for 89.3% of the samples. Histopathology was more sensitive than other ancillary tests for diagnosing tuberculosis. Paraffin-embedded tissues from lymphoma cases were subjected to immunophenotyping using anti-CD3 and anti-CD79a immunohistochemistry. Frozen and/or paraffin-embedded tissues from lymphoma cases were used to identify the enzootic bovine leukosis (EBL) retrovirus through qPCR. Other diagnoses included primary (T- and B-cell lymphoma) and metastatic neoplasms (squamous cell carcinoma, pulmonary adenocarcinoma, undifferentiated carcinoma, undifferentiated adenocarcinoma, undifferentiated sarcoma, undifferentiated round cell tumor, mesothelioma, hepatic carcinoid, meningioma, and seminoma), actinogranulomas (pyogranulomatous lymphadenitis [actinobacillosis and actinomycosis]), idiopathic lymphadenitis (neutrophilic and/or histiocytic, granulomatous, and suppurative), and miscellaneous nonspecific lymphadenopathies (depletion/lymphoid atrophy, lymphangiectasia, erythrocyte drainage, parasitic eosinophilic lymphadenitis, follicular hyperplasia, and toxic granulomatous lymphadenitis). The combination of histopathology with complementary techniques is important for successful diagnosis, especially in complex cases of high epidemiological, economic, and zoosanitary importance, such as tuberculosis and EBL.

[Multicentric B cell lymphoma in an 8-week-old calf]

The presented report describes a case of sporadic bovine leukosis and its disease progression in an 8-week old, male cross-breed calf (Red Holstein Fleckvieh). The calf was initially presented due to suspect pulmonary infection. However, generalized enlargement of the subcutaneous lymph nodes was noticed, which is untypical for this disease. Based on the hematologic findings of highly increased numbers of lymphoblasts in peripheral blood as well as the sonographic examination of the lymph nodes, sporadic bovine leukosis was suspected. The calf died suddenly, three weeks after initial presentation. Pathohistological examination revealed a high-degree enlargement of all lymph nodes as well as an infiltration of nearly all organs and tissues with a monomorphic round cell population. These cells were also detected in bone marrow cytology. Immunhistochemical examination was performed and the cells reacted positive for the B-cell markers Pax 5 and CD20. Virologic examination for enzootic bovine leukosis was negative. In conjunction with the diagnosis of multicentric B-cell lymphoma, the test results indicated a juvenile form of sporadic bovine lymphoma.

Establishment of a simplified inverse polymerase chain reaction method for diagnosis of enzootic bovine leukosis

Enzootic bovine leukosis (EBL) is a malignant B-cell lymphoma of cattle caused by infection with bovine leukemia virus (BLV). It is defined by clonal and neoplastic expansion of BLV-infected B cells. Currently, multiple examinations are able to comprehensively diagnose this condition. Inverse polymerase chain reaction (PCR) is a useful method to determine retrovirus integration sites. Here, we established a simplified inverse PCR method, involving the evaluation of clonality and similarity of BLV integration sites, to clinically diagnose EBL, and we also assessed its reliability. We found that the novel BLV inverse PCR could detect clonal expansion of infected cells even if they constituted only 5% of the total number of cells, while not amplifying any fragments from BLV-uninfected cells, thus confirming its sufficient sensitivity and specificity for use in EBL diagnosis. Furthermore, 50 clinical cases of bovine leukemia were analyzed using BLV inverse PCR and other PCR-based methods, wherein our method most efficiently determined virus-dependent bovine leukemia, including unidentified clinical cases observed in a previous report. Following further clinical investigations to enhance its reliability, the proposed BLV inverse PCR method has the potential to be applied to EBL diagnosis.

Development of an in situ hybridization assay using an AS1 probe for detection of bovine leukemia virus in BLV-induced lymphoma tissues

Enzootic bovine leukosis (EBL) is a malignant B cell lymphoma caused by infection with bovine leukemia virus (BLV). Histopathological examination is commonly used for diagnosis of the disease, but observation of lymphoma alone does not confirm EBL because cattle may be affected by sporadic forms of lymphoma that are not associated with BLV. Detection of BLV in tumor cells can be definitive evidence of EBL, but currently, there is no technique available for such a purpose. In this study, we focused on a viral non-coding RNA, AS1, and developed a novel in situ hybridization assay for the detection of BLV from formalin-fixed paraffin-embedded (FFPE) tissues. RNA-seq analysis revealed that all examined B lymphocytes derived from clinical EBL abundantly expressed AS1 RNA, indicating a possible target for detection. The in situ hybridization assay using an AS1 probe clearly detected AS1 RNA in fetal lamb kidney cells persistently infected with BLV. The utility of this assay in clinical samples was assessed using three EBL-derived lymph node specimens and one BLV-negative specimen, and AS1 RNA was detected specifically in the EBL-derived tissues. These results suggest that AS1 RNA is a useful target for the detection of BLV from FFPE specimens of tumor tissues. This technique is expected to become a powerful tool for EBL diagnosis.

Disseminated thymic B-cell lymphoma in a Holstein heifer

A 19-mo-old Holstein heifer was inactive and dyspneic. Physical examination revealed wheezing, exophthalmos, a cervical mass, and lymphadenopathy. Cytology of the cervical mass and lymph nodes showed predominantly large atypical lymphocytes. Lactate dehydrogenase and thymidine kinase activities were elevated. Although nested PCR for bovine leukemia virus (BLV) using blood was positive, quantitative PCR showed a low number of provirus copies. Autopsy revealed enlargement of most lymph nodes examined, as well as white masses of various sizes in muscles of the left hindlimb and thoracic and abdominal organs. Histopathology revealed severe infiltration with neoplastic lymphocytes in these organs. The cervical mass was immune-positive for B-cell markers. The final diagnosis was thymic B-cell lymphoma with BLV infection.

Identification of an Atypical Enzootic Bovine Leukosis in Japan by Using a Novel Classification of Bovine Leukemia Based on Immunophenotypic Analysis

Bovine leukemia is classified into two types: enzootic bovine leukosis (EBL) and sporadic bovine leukosis (SBL). EBL is caused by infection with bovine leukemia virus (BLV), which induces persistent lymphocytosis and B-cell lymphoma in cattle after a long latent period. Although it has been demonstrated that BLV-associated lymphoma occurs predominantly in adult cattle of >3 to 5 years, suspicious cases of EBL onset in juvenile cattle were recently reported in Japan. To investigate the current status of bovine leukemia in Japan, we performed immunophenotypic analysis of samples from 50 cattle that were clinically diagnosed as having bovine leukemia. We classified the samples into five groups on the basis of the analysis and found two different types of EBL: classic EBL (cEBL), which has the familiar phenotype commonly known as EBL, and polyclonal EBL (pEBL), which exhibited neoplastic proliferation of polyclonal B cells. Moreover, there were several atypical EBL cases even in cEBL, including an early onset of EBL in juvenile cattle. A comparison of the cell marker expressions among cEBL, pEBL, and B-cell-type SBL (B-SBL) revealed characteristic patterns in B-cell leukemia, and these patterns could be clearly differentiated from those of healthy phenotypes, whereas it was difficult to discriminate between cEBL, pEBL, and B-SBL only by the expression patterns of cell markers. This study identified novel characteristics of bovine leukemia that should contribute to a better understanding of the mechanism underlying tumor development in BLV infection.

Multicentric lymphoma in buffaloes in the Amazon region, Brazil

Background

The presence of lymphoma in buffaloes was first reported in India in the 1960s. The disease is similar to Enzootic Bovine Leucosis (EBL) caused by Bovine leukemia virus (BLV) in cattle; however, according to our results and those of other studies, the etiology of these lymphomas in buffalo do not appear to be associated with BLV. The objectives of this study are to describe four cases of the disease in buffaloes belonging to the same herd in the Amazon region of Brazil and to perform a clinical-anatomopathological, immunohistochemical, and etiological study of the lymphomas.

Results

Over a period of ten years, four buffaloes were observed presenting progressive weight loss, swelling of peripheral lymph nodes, and nodules in the subcutaneous tissue. Upon necropsy, whitish-colored tumor masses were observed in the form of nodules in the subcutaneous tissue, along with miliary nodules on the serosal surfaces of abdominal and thoracic organs and tumors in lymph nodes and other organs. Neoplastic lymphocyte proliferation was observed through histopathology. An immunohistochemical study revealed that the neoplasias were formed by proliferation of predominantly B lymphocytes. The presence of BLV genome was not detected in the lymphomas when using the real-time PCR technique, nor was it detected through immunohistochemical staining using monoclonal antibodies against two viral proteins. Bovine herpesvirus 6 was not detected in the tumors. However, Bovine immunodeficiency virus (BIV) was detected in samples of lymphoma and in the lymph nodes and kidneys of one of the animals.

Conclusions

The occurrence of lymphoma in buffaloes is reported for the first time in Brazil and is characterized by B-cell multicentric lymphoma. The etiology of the disease does not appear to be associated with BLV; however, the detection of BIV in samples of lymphoma from one sick animal deserves further study, considering the oncogenic potential of this virus.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0845-y) contains supplementary material, which is available to authorized users.

T-cell lymphoma in the nasal cavity of a Brown Swiss heifer

Background

Tumours of the upper respiratory tract are relatively common in cattle, but to our knowledge, there have been no reports of lymphoma of the nasal cavity. This case report describes the findings in a 22-month-old Brown Swiss heifer with T-cell lymphoma of the nasal cavity.

Case presentation

The main clinical findings were lacrimation and swelling of the head above and below the right eye, mild exophthalmos, third eyelid prolapse, purulent ocular discharge and congestion of scleral blood vessels. An endoscope could only be introduced a few centimetres into the right nasal cavity because of an obstructing mass in the nasal passage. Radiographs showed a mass in the right nasal cavity and maxillary sinus. A tentative diagnosis of neoplasia of the right nasal cavity was made and the heifer was euthanased and necropsied. A firm, tan mass measuring 10 by 13 by 15 cm in the right half of the head occupied the entire right nasal cavity. A final diagnosis of high-grade, malignant, small-sized T-cell lymphoma was made based on histological and immunohistochemical evaluation. A distinction between αβ T-cell or γδ T-cell lymphoma was not made.

Conclusions

This report on T-cell lymphoma in the nasal cavity of a cow suggests that nasal lymphoma should be included in the list of differential diagnosis of conditions associated with dyspnoea and stertorous breathing in cattle.