Renal histiocytic sarcoma in a cat undergoing nephrectomy and adjuvant chemotherapy

A 6-year-old, male neutered, domestic shorthair cat was presented for further investigation of a right-sided kidney mass. A contrast-enhanced computed tomography scan of head, thorax and abdomen showed a right-sided renal mass, with infiltration of the surrounding tissue, but no evidence of distant metastasis. Cytology was consistent with a poorly differentiated neoplasia, and nephrectomy was performed. Following surgery, the cat underwent multiple blood transfusions due to severe anaemia and developed tricavitary effusion compatible with a protein-rich transudate. The tumour was confirmed to be a histiocytic sarcoma on histopathology and immunohistochemistry, and the patient received adjuvant chemotherapy with lomustine. Restaging procedures were performed 121 days following surgery and documented recurrence at the previous surgical site together with cutaneous metastasis, therefore a rescue protocol with single agent doxorubicin was started. The patient was euthanased after worsening of its clinical conditions, 152 days since nephrectomy was performed.