Cutaneous T-cell lymphoma with Sézary syndrome in a dog

An 8-year-old female spayed Cocker Spaniel mix breed dog was presented with generalized erythroderma, scaling and alopecia. Radiographs of the thorax demonstrated a discrete lung mass which was aspirated using ultrasound guidance and cytological analysis revealed large abnormal lymphocytes. Similar cells were observed in the peripheral blood and in skin biopsies. The cells in the skin biopsies were epidermotropic, indicative of an uncommon cutaneous lymphoma termed cutaneous T cell lymphoma (CTCL), sometimes also called mycosis fungoides. Immunohistochemical staining of a skin biopsy was positive for the CD3 antigen demonstrating that the lymphocyte infiltrate was of a T-cell lineage. The presence of neoplastic lymphocytes in the epidermis and peripheral blood indicate that this is a rare variant of Cutaneous Epidermotropic Lymphoma (CEL) called Sézary syndrome based on nomenclature used in the human literature. An unusual feature of this dog, not seen in previous cases, was the presence of a discrete neoplastic lung mass.