Extreme lymphocytosis in a dog with T-zone lymphoma.

Background: Canine T-zone lymphoma (TZL) is recognized as an indolent CD45-T cell lymphoma, with low aggressiveness and high overall survival. The diagnosis is obtained by histopathology and immunohistochemistry, but also by cytological examination of the lymph node associated with immunophenotyping. Lymphocytosis is commonly identified as around 10,000 cells/µl and may reach 30,760 cells/µl. Case Description: The present report describes a case of a female Golden Retriever, nine years old, with generalized lymphadenopathy. In the cytological examination of the superficial cervical lymph node, a monomorphic population of small, "clear cells" and "hand mirror" lymphocyte shape was suggestive of TZL. The leukogram showed intense leukocytosis (160,050 cells/µl) due to small clear cell lymphocytosis (152,048 cells/µl). The myelogram showed a myeloid:erythroid ratio of 2:3; with a pyramidal distribution of cell types and the presence of 22.8% of lymphocytes in the differential count. Bone marrow, peripheral blood, and lymph node immunophenotyping resulted in lymphocyte gates with 97.3% to 99.5% CD5+, predominantly CD4-, CD8-, and CD45- confirming the diagnosis of TZL with associated leukemia. Treatment with chlorambucil and prednisolone was started. During the first month, the lymphocytosis remained above 200,000 cells/uL. After four months of treatment, there was a decrease in lymphocytes, which progressively reached a count of 10,800 cells/ul in the eleventh month. Conclusion: In the literature, lymphocytosis above 30,760 cells/µl has not been observed in TZLs. Thus, it is believed that this is the first report of extreme lymphocytosis with a slow response to chemotherapy.

Clinical, histological, immunohistochemical and genetic factors associated with measurable response of high-risk canine mast cell tumours to tyrosine kinase inhibitors.

The aim of the present prospective-retrospective study was to evaluate the response of high-risk canine mast cell tumours (MCTs) to tyrosine kinase inhibitors (TKIs) and to correlate this with prognostic factors. A total of 24 dogs presented with macroscopic cutaneous MCTs at disease stage II or III, and therefore, at high-risk of associated mortality, were included in the study and treated with masitinib (n=20) or toceranib (n=4). A total of 12/24 dogs achieved an objective response and the overall survival (OS) for all subjects was 113 days. Dogs responding to treatment had a significant increase in OS compared to non-responders (146.5 days vs. 47 days, P=0.02). Internal tandem duplications in exon 11 of the c-kit gene were identified in 6/24 cases. Ki67, KIT immunolabelling and c-kit mutation did not provide information regarding prognosis or prediction of response to TKIs in this population. Initial response to TKIs appears to be the most reliable prognostic factor for survival duration.

Fatores prognósticos e preditivos dos tumores caninos definidos com auxílio da imuno-histoquímica / Prognostic and predictive factors of canine tumours defined with immunohistochemistry's assistance

A imuno-histoquímica pode ser aplicada na oncologia veterinária para a definição do imunofenótipo neoplásico, com possibilidades ilimitadas de utilização. A técnica baseia-se na identificação de antígenos "in situ", que podem apresentar valor prognóstico e terapêutico. A expressão de receptores de estrógeno e progesterona está diretamente relacionada ao melhor prognóstico para os neoplasmas mamários, enquanto a super-expressão do receptor KIT (CD117), proteínas Ki-67 (MIB-1), VEGF, CD31 e COX-2 podem ser associados à progressão tumoral para vários tipos histológicos. Essa associação possui valor preditivo em potencial, tendo em vista a possibilidade da utilização de bloqueadores específicos. Esta revisão tem como objetivo apresentar as possibilidades da utilização da imuno-histoquímica nos tumores de cães, visando à definição mais precisa do prognóstico e a indicação de tratamentos específicos para cada paciente.

Immunohistochemistry can be applied in veterinary oncology to define the immunophenotype of neoplastic cells with unlimited possibilities of application. The technique is based on the identification of antigens "in situ", which may have prognostic and therapeutic value. Expression of estrogen and progesterone is directly related to better prognosis for breast cancer, while over-expression of receptor KIT (CD117) proteins Ki-67 (MIB-1), COX-2, VEGF and CD31 can be associated with tumor progression for several histological types. This association has a potential predictive value, due to the possibility of using specific blockers. This revision aims at presenting the possibilities of immunohistochemical's application in tumors of dogs, searching for a more precise definition of the prognosis and indication of specific treatments for each patient.