Case of the Month

• Very large retroperitoneal space-occupying lesion in the region of the left kidney with severe diffuse retroperitoneal effusion/bleeding. Most likely consistent with a bleeding neoplasia originating from the left kidney such as round cell neoplasia, especially histiocytic sarcoma, or an adenocarcinoma. Other neoplasias not to exclude. Granulomatous disease much less likely. Origin of the mass from the left adrenal less likely.

• Moderate nephromegaly right. Differentials: metastatic/neoplastic enlargement, compensatory hypertrophy. Other differentials less likely.

• Multiple nodular pulmonary lesions, most likely consistent with pulmonary metastasis.

• Hypovolemia.

• If desired from the owner abdominal ultrasound with tissue sampling for definitive diagnosis to be considered. Alternatively, if desired from the owner, exploratory celiotomy to be considered.

• A left renal mass was ultrasonographically confirmed. No further follow up was provided for this case. 

• More about Primary Renal Neoplasia of Dogs (click on the link).

• Some literature: Computed tomographic features of renal neoplasms in dogs.

Thorax and abdomen in 3 projections of a skeletally mature dog in mild increased body condition.

Mild spondylosis deformans at L4-5. Musculoskeletal structures otherwise within normal limits.

Thorax:

Diaphragm delineable. Thoracic volume normal.

Mediastinum within normal limits.

Cardiac silhouette small/hypovolemic. Pulmonary vessels within normal limits. Caudal vena cava thin, consistent with hypovolemia.

Pulmonary parenchyma with two large well-defined spheric homogeneous soft tissue opaque lesions, one in the right caudal and one in the left caudal lung lobes. One additional small nodularity soft tissue opaque lesion in the right cranial lung lobe.

Abdomen:

Peritoneal detail maintained.

Retroperitoneal detail severely patchy and moderately reduced, mainly on the left side.

Very large moderately well-defined ovoid mostly homogeneous soft tissue opaque retroperitoneal space-occupying lesion in the region of the left kidney with loss of the visibility of the left kidney. Right kidney generalized moderately enlarged with ovoid shape and mild irregular contour. Urinary bladder mildly filled and in normal position.

Liver not extending caudally to the rib cage.

Splenic head in normal position.

Stomach mildly filled with gas. Small bowel loops empty or very mildly filled with gas. Colon mildly filled with gas and formed feces.

Very large retroperitoneal space-occupying lesion in the region of the left kidney with severe diffuse retroperitoneal effusion/bleeding. Most likely consistent with a bleeding neoplasia originating from the left kidney such as a round cell neoplasia, especially histiocytic sarcoma, or an adenocarcinoma. Other neoplasias not to exclude. Granulomatous disease much less likely. Origin of the mass from the left adrenal less likely.

Moderate nephromegaly right. Differentials: metastatic/neoplastic enlargement, compensatory hypertrophy. Other differentials less likely.

Multiple nodular pulmonary lesions, most likely consistent with pulmonary metastasis.

Hypovolemia.

If desired from the owner abdominal ultrasound with tissue sampling for definitive diagnosis to be considered. Alternatively, if desired from the owner, exploratory celiotomy to be considered.