Presentation
Remy is a 4-year-old male neutered Corgi that first presented to their primary care vets with a presenting complaint of hyporexia. On further investigation, the referring vets discovered a large mid-abdominal mass on radiographs and ultrasound. The patient was then referred to VES for an internal medicine consultation with Dr Pauline Jamieson for further diagnostics.
Upon review of the radiographs in VES, it was difficult to determine the origin of the mass. While a hepatic or splenic mass was suspected, it was difficult to come up with differentials, or determine if the mass was resectable just based on radiographs alone. Hence, a decision was undertaken to run a CT scan on Remy – this would allow us to better identify which structures the mass interacted with, and how extensive surgery needs to be.
LEARNING POINT #1: What are the benefits of a CT scan over traditional imaging methods like radiographs and ultrasound?
- CT scans offer greater soft tissue contrast and can differentiate between various types of tissues more effectively. This can help in distinguishing between benign and malignant masses, cysts or abscesses.
- CT scans reveal how a mass interacts with adjacent structures (e.g. blood vessels, lymph nodes), to determine whether a patient is a good surgical candidate.
- CT scans are more sensitive in detecting multiple lesions, which can indicate specific disease processes (e.g. metastasis, multicentric tumors) and aid in forming more accurate differentials. It is also not as operator dependant as an ultrasound – for example, in an abdomen where intestinal gas can obstruct proper visualisation of structures in ultrasound, CT scan will allow better visualisation of organs with less interference.
In the images below, we will highlight some structures for you on Remy’s CT scan to appreciate the differences!
CT Scan Findings
How do we know which structures the abdominal mass is interacting with? By looking closely at the CT scan, of course!
The CT scan showed the abdominal mass to be in close contact with the cranial pole of the left kidney, extending close to the spleen and along the lesser curvature of the stomach (seen in Fig 1).
Presence of blood vessels between the kidney and the mass itself, together with the mass deforming the renal capsule, are two key features confirming the renal origin of the mass (seen in Fig 2).
In addition, the CT shows us that the main vasculature of the spleen was running in very close contact with the mass (seen in Fig 3), which might complicate surgery.
Based on the CT scan findings, a FNA or Tru-cut biopsy were deemed to be too unsafe as the mass was clearly vascular and there was a risk of haemorrhage. A surgery was recommended for full resection of the mass to aim for treatment and definitive diagnosis, and the owner decided to go ahead with surgery with our surgeon Dr Naomi Shimizu.
Decision Making in Surgery
Going into surgery, there was uncertainty as to whether there was adhesion of the mass with adjacent organs and blood vessels. While CT showed close contact of the mass with the liver, spleen and splenic vessel, you can never really tell if the mass is fully adherent to the structures, or just adjacent to them, until you are actually in surgery.
In this case, we found that only the splenic vasculature was completely embedded within the mass. However, the surrounding tissue was friable which led to bleeding even with gentle manipulation of the mass. In such cases, there is a delicate balance between being careful yet quick enough – dissection needs to be patient and gentle in order to free important structures from the mass, but at the same time, you also need to be fast to avoid the mass rupturing from manipulation before ligation of important vessels!
It was certainly not an easy surgery, but fortunately, after the mass was removed via a left nephrectomy and splenectomy, no further bleeding was observed, and further exploration of the abdomen did not show any gross abnormalities or metastasis.
Now that we know the origin of the mass is the left kidney, what are some of the differentials we can come up with?
Click here to see a list of differentials that Dr Naomi came up with.
Here are all the differentials that Dr Naomi will have to rule out with histopathology:
- Renal carcinoma
- Transitional cell carcinoma
- Nephroblastoma
- Cystadenocarcinoma
Click here to see the definitive diagnosis and prognosis.
The histopathology results came back for renal cell carcinoma, and noted that the spleen and liver were clear of disease.
- Renal cell carcinomas are common neoplasias in dogs and cats. This is a malignant tumour that can metastasise to regional lymph nodes as well as other abdominal organs and lungs. These masses do not respond to chemotherapy and therefore the best treatment is surgical, assuming no metastasis is already present.
- The median survival time is 8-16 months for dogs with renal carcinoma. However, surgical resection has resulted in prolonged survival times of up to 4 years in cases where no metastatic disease was present at diagnosis.
Learning point #2: Don’t give up!
It can sometimes be easy to assume the worst when we find a large mass in our patients on diagnostic imaging, but not every large abdominal mass has terrible prognosis! Even if they invade structures, some of these masses (like renal cell carcinomas) can be surgical and can give a prolonged survival time of a few years if surgical intervention is successful.
Post-op care is generally routine with 6 monthly checks for metastasis, and patients can continue to have great quality of life post-surgery.
Conclusion
Remy has done very well post-surgery, much to the delight of his owners and our team! We will continue to monitor Remy for any neoplastic spread/recurrence, as well as his urea and creatinine levels to ensure his other remaining kidney is ticking along just fine. In the meantime, he will continue to live his life to the fullest!
