Case Study

Retroperitoneal carcinoma and bladder stones in a 11 year old MN Cock-a-poo dog

An 11-year-old MN Cock-a-poo was presented for PU/PD for 2 months, lethargy, vomiting, and straining to defecate. On physical examination, pyrexia and a grade II/VI systolic murmur was present. CBC and blood chemistry were within normal limits. On survey radiographs a caudal abdominal mass around the urinary bladder was evident. The thoracic cavity was within normal limits.

DX

Retroperitoneal carcinoma. Cystic calculi.

Sonographic Differential Diagnosis

Multiple abscesses with lymphadenopathy presumable deriving from the prostate with potential neoplastic origin. Caudal abdominal peritonitis.

Image Interpretation

The urinary bladder was enveloped by multiple cysts and abscesses, which appeared to be arising from the prostate or regional lymph nodes.This all appeared to derive from the left prostatic lobe and is likely due to a long history of prostatitis and abscessation (this origin could not be confirmed). It has now likely progressed into multiple abscesses with local peritonitis. A minor amount of free fluid was present adjacent to these abscesses.

Outcome

Surgical debulking, lymph node biopsy in the region of the prostate, cystotomy, anaerobic and aerobic cultures of the abscessing tissue, and inspection of the liver were strongly recommended. Upon presentation at a referral facility, the patient’s temperature was 106.4. Abnormalities on pre-operative blood work were neutrophilia, lymphopenia, mildly elevated ALP activity, and mild hypokalemia. Exploratory surgery was performed in which the liver appeared normal, a single solid retroperitoneal mass was excised, multiple cystic masses were incised and drained, and a cystotomy performed. 24 hours post-operative the patient had a positive fluid wave, was straining to defecate, and leaking urine. The patient was discharged to the care of his owners with Clavamox, Baytril, tramadol, and lactulose pending histopathology results.

Comments

The patient was lost to follow up. Even though the origin could not be confirmed, usually the only structures in this region that form cysts are the prostate and paraprostatic cysts. Ureters were normal, and the patient was not a hermaphrodite, which could theoretically form uterine dilation/pyometra. Therefore, by deduction, prostate was considered the primary suspect especially since carcinoma was confirmed on the surgical biopsy.

Clinical Differential Diagnosis

Caudal abdominal mass – prostatic disease (neoplasia, abscess, granuloma), bladder pathology (neoplasia, previous rupture with adhesions). Other source of abdominal neoplasia, cyst, abscess, granuloma.