Immunohistochemical profile of multicentric cutaneous epitheliotropic T-cell lymphoma with generalised lymphadenopathy in a Holstein-Friesian cow: a case report.

Cutaneous epitheliotropic T-cell lymphoma with progression to superficial and internal lymph nodes and the spleen was diagnosed in a two-year-old Holstein-Friesian cow. The skin lesions included multiple hypotrichous to alopecic nodules, often with ulceration, which first appeared three months after calving and progressed quickly to cover the entire body. The cow was euthanized one month later. The ELISA test excluded bovine leukaemia virus infection. Histologically in the epidermis, the formation of Pautrier's microabscesses and in the dermis, dense neoplastic infiltration with mild folliculotropism was observed. Similar neoplastic cells were present in the histological sections of lymph nodes and spleen. Immunohistochemical analysis was performed using CD3, CD79αcy, HLA-DR, WC1-N3 and Ki67 antibodies. Immunophenotyping results (CD79αcy-, CD3+, WC1-N3-) confirmed the αβ T-cell origin of neoplastic cells. The mean Ki67 index among neoplastic cells was 15.3%. On the basis of the immunohistochemical and histopathological results, the first case in Poland of cutaneous epitheliotropic T-cell lymphoma in a cow was confirmed. Additionally, MHC class II expression on approximately 10.4% of lymphoma cells was associated with a poor clinical prognosis. However, the up-regulation of MHC class II expression on accompanying cells suggested tumour immune surveillance, an antigen-specific immune response or immunosuppression. However, further investigations are needed to confirm these suspicions.