Successful surgical treatment of a prostatic biphasic tumour (sarcomatoid carcinoma) in a cat.

A 12-year-old, neutered male, mixed-breed, domestic cat was presented for dysuria and haematuria accompanied by recurrent dyschezia and constipation. At rectal digital examination a non-painful, globose and relatively immobile mass was detected at the pelvic brim, ventral to the rectum. Abdominal ultrasound showed the prostate replaced by a mass with a regular shape but patchy/non-uniform echogenicity. A prostatectomy followed by prepubic urethrostomy was performed. At histopathology the tumour was composed of epithelial ducts and acini with malignant features, surrounded by proliferating cellular stroma with mitoses and nuclear atypia; an immunohistochemical panel confirmed the biphasic nature of the tumour proliferation. The diagnosis was non-infiltrating malignant mixed tumour, resembling human sarcomatoid carcinoma of the prostate. Two years after surgery the animal has not shown any health problems. To the author's knowledge, this is the first reported case of prostatic tumour with a positive follow-up after surgical treatment in cat.