2008 Radiology Exam - Spec Proced/NM Case 2

Signalment: 11 year old Spayed female Golden retriever

History: Abdominal Pain, weight loss and anorexia

Candidate was presented with survey lateral and VD radiographs. Selected views of an excretory urogram were presented at a later stage.

See images below. Click to enlarge.

Survey findings: There is a severe left renomegaly. On the lateral projection the renal enlargement causes a mass effect of retroperitoneal origin which displaces the proximal aspect of the descending colon ventrally. The affected kidney is irregular. The right kidney was not visualized on the VD projection. Skin folds can be clearly seen of the VD projection.

Excretory urogram: There is asymmetric renal opacification at 15 and 30 minutes after contrast injection. There is a decrease opacification of most of the left renal parenchyma which is characterized by large filling defects of ill defined borders. Complete absence of the left pyelographic phase was also detected. The right kidney exhibits a normal nephrographic and pyelographic phases. The right ureter is within normal limits in diameter and can be noted entering the urinary bladder in a normal orientation. The urinary bladder has a mild to moderate volume of contrast material at 15 minutes post contrast injection.

Conclusions: Left renomegaly with multiple filling defects likely the result of the presence of several renal masses. The process has replaced the renal parenchyma to the point there is a poor nephrographic phase and complete absence of a pyelographic phase.

Differential diagnoses: Renal neoplasia such as adenocarcinoma is the most likely possibility. Other less likely possibilities should include a renal abscess or a granuloma. The excretory urogram findings made the possibility of hydronephrosis or polycystic renal disease less likely. Final diagnosis (histopathology): renal adenocarcinoma.

Candidate performance: Candidates were expected to identify without ambiguity the presence of a retroperitoneal mass of renal origin. They were also expected to generate a list of differential diagnoses based on the increase renal size AND shape of the affected kidney. They were also expected to recognize and describe the filling defects along with an organized assessment of the different phases of the renogram. It was expected that the candidates would ask for an ultrasound or an excretory urogram. Most candidates generated a list of appropriate differential diagnosis based on the survey radiographs but struggled to further prioritize their list once the excretory urogram findings were known. Most candidates do not have a “polished” method to assess the excretory urogram in terms of renal opacification, presence or absence of the study’s phases and characteristics of the filling defects. A few candidates did not go back to the survey radiographs to correlate both pre- and post-contrast findings. Most candidates passed the case.