Prostatic hemangiosarcoma in a dog: clinical and pathologic findings.

Abstract

Prostatic hemangiosarcoma (HS) appears to be rare in the dog. In 3 of 4 previously reported cases, the prostate was involved via metastasis. For 1 dog, the primary tumor presumably was located in the prostate gland, but no details were given. The present report documents what we believe is a primary HS of the prostate in a dog that presented with clinical signs of urinary tract disease. The prostate tumor and metastases had microscopic features of a poorly differentiated HS, and the diagnosis was confirmed by immunohistochemistry. An 11-year-old male Miniature poodle was admitted to a veterinary hospital because of straining to urinate and defecate and passing “ribbon-like” feces for approximately 1 month. Physical examination revealed prostatomegaly. The dog was castrated and given an injection of 0.25 mg of estradiol cypionate intramuscularly. Clinical signs persisted, and the dog was referred to the University of Minnesota Veterinary Teaching Hospital (UMVTH) 6 days after castration. Physical examination revealed a thin dog with prostatomegaly and a very distended urinary bladder. A complete blood count revealed a normochromic normocytic anemia (PCV = 23%, normal > 37%) without significant regenerative response. The dog was catheterized without difficulty, and 225 ml of yellow urine were removed. A urinalysis was consistent with urinary tract infection, and a urine culture revealed Klebsiella pneumoniae and Proteus mirabilis (> 10 colony forming units/ml). Prostatomegaly was identified on abdominal radiographs. A sonogram revealed diffuse prostatic hyperechogenicity with irregular multifocal hypoechoic masses. A prostatic biopsy was performed with a Tru-Cut biopsy needle via a perineal approach. Microscopic examination revealed neoplastic polyhedral and spindle cells of uncertain tissue type. Following a course of radiation therapy, which failed to shrink the prostate, the dog was euthanized. At necropsy, the prostate gland protruded from the cranial rim of the pelvis and was tightly adhered to the pelvic canal, especially on the right side. Although both lobes of the prostate were enlarged, the right lobe was more severely affected. The prostate was 10.5 x 6.0 x 4.0 cm and weighed 125 g. Transverse sections of the prostate revealed a large yellow core encircled by a rim of red tissue. Reddish-yellow tissue was present within the right obturator foramen. Soft red and white nodules 0.7 cm and 4 cm in diameter were found in the left and right medial thigh muscles, respectively.