Your pathology report for tubulocystic renal cell carcinoma

Jason Wasserman MD PhD FRCPC
June 14, 2025

Tubulocystic renal cell carcinoma (TcRCC) is a rare type of kidney cancer. It begins in very small tubes (tubules) and cysts within the kidney. A cyst is a small sac filled with fluid. These tumours typically have a cystic appearance, meaning they contain multiple small cysts. Tubulocystic renal cell carcinoma is usually a slow-growing tumour and generally has a good prognosis.

What are the symptoms of tubulocystic renal cell carcinoma?

Most people with tubulocystic renal cell carcinoma have no noticeable symptoms. These tumours are often discovered accidentally during imaging tests (such as CT or MRI scans) done for unrelated health reasons.

When symptoms do occur, they might include:

• Blood in the urine, causing urine to appear pink, red, or brown.

• Pain or discomfort in the abdomen or side.

• In very rare cases, this tumour may affect kidney function and contribute to end-stage kidney disease.

These symptoms can also occur with many other kidney conditions, so doctors use tests to confirm the diagnosis.

What causes tubulocystic renal cell carcinoma?

Doctors currently do not know exactly what causes tubulocystic renal cell carcinoma. Most tumours occur randomly, without an identifiable reason. Researchers continue to study whether genetics or environmental factors might contribute to its development.

Who is most likely to get tubulocystic renal cell carcinoma?

Tubulocystic renal cell carcinoma is quite rare, accounting for less than 1% of kidney tumours. It occurs more commonly in men than in women. Most people diagnosed are adults, typically between 30 and 74 years of age, with an average age of around 58.

How is tubulocystic renal cell carcinoma usually diagnosed?

Tubulocystic renal cell carcinoma is often found accidentally during imaging tests like ultrasound, CT, or MRI scans of the abdomen performed for unrelated reasons. On these scans, the tumour appears as a mass with multiple small cysts within the kidney.

If doctors suspect tubulocystic renal cell carcinoma, they may suggest surgery to remove the tumour. A biopsy (a procedure to take a small piece of the tumour for examination) is sometimes performed to confirm the diagnosis before surgery. However, the entire tumour is often removed first and examined closely by a pathologist.

What does tubulocystic renal cell carcinoma look like under the microscope?

Under the microscope, tubulocystic renal cell carcinoma has unique features. The tumour is made up of:

• Small tubes (tubules) and larger cysts filled with clear fluid.

• Cells lining these tubes and cysts appear flattened, cuboidal (square-shaped), or hobnail-shaped (round with a bump-like appearance).

• Tumour cells have irregular and enlarged nuclei with prominent nucleoli (small structures within the nucleus), giving them a distinctive appearance.

• The supporting tissue (called stroma) often looks dense or scarred (fibrotic).

These features help pathologists make a clear diagnosis of tubulocystic renal cell carcinoma and distinguish it from other types of kidney tumours.

What does tumour extension mean, and why is it important?

Tumour extension describes how far the tumour has grown beyond the kidney into nearby tissues or structures. As a tumour grows, it may expand into surrounding fat, large veins, or other nearby organs or structures. Tumour extension is carefully assessed and documented in your pathology report because it helps determine the tumour’s stage and may influence treatment decisions. Tumours confined to the kidney generally have a better prognosis compared to those that have extended beyond the kidney.

What is a surgical margin, and why is it important?

A surgical margin is the healthy tissue around a tumour that surgeons remove during surgery. Pathologists examine these margins carefully under a microscope to check for tumour cells at the edge.

• Negative margin: No tumour cells are found at the edge of the tissue. This means the tumour was completely removed and there is a lower chance it will grow back.

• Positive margin: Tumour cells are present at the edge of the tissue. A positive margin might suggest that some tumour remains, and further treatment may be necessary.

Your doctor will clearly discuss your margin status and advise whether any additional procedures or treatments are recommended.

What is lymphovascular invasion, and why is it important?

Lymphovascular invasion means tumour cells have entered small blood vessels or lymph vessels. Lymph vessels connect to small immune organs called lymph nodes. Tumours with lymphovascular invasion have a higher risk of metastasizing (spreading) to other body parts. If lymphovascular invasion is identified, it will be clearly noted in your pathology report, and your doctor may recommend closer monitoring or additional treatment.

Were lymph nodes examined, and what does it mean if tumour cells are found?

Lymph nodes are small, bean-shaped immune organs located throughout the body. Cancer cells can sometimes spread to lymph nodes through lymphatic vessels.

If lymph nodes were removed during surgery, your pathology report will state clearly how many lymph nodes were examined and whether any contain tumour cells.

• Negative lymph nodes: No tumour cells found in any of the lymph nodes examined. This means the tumour likely has not spread to nearby lymph nodes.

• Positive lymph nodes: Tumour cells are found in one or more lymph nodes examined. Positive lymph nodes mean the tumour has spread and could require additional treatment, such as chemotherapy or immunotherapy.

What is the prognosis for tubulocystic renal cell carcinoma?

In most cases, pure tubulocystic renal cell carcinoma grows slowly and has an excellent prognosis. It rarely spreads and does not cause serious health issues. However, very rare cases have been reported where this tumour has spread. Your doctor will discuss your specific case and outlook with you based on the details of your pathology report.

Pathologic staging (TNM system) for tubulocystic renal cell carcinoma

Your doctor uses the TNM staging system to clearly describe how advanced the tumour is. This helps determine appropriate treatment and prognosis.

Tumour stage (T)

• T1: Tumour is 7 cm or smaller and fully within the kidney.

• T2: Tumour is larger than 7 cm but still entirely within the kidney.

• T3: Tumour has grown into nearby fat or a large vein attached to the kidney.

• T4: Tumour has grown beyond the kidney into surrounding organs or through Gerota’s fascia (the protective layer around the kidney).

Lymph node stage (N)

• N0: No tumour cells found in lymph nodes.

• N1: Tumour cells found in lymph nodes.

• NX: No lymph nodes examined.

Metastatic stage (M)

• M0: No spread to distant body parts.

• M1: Tumour has spread to distant parts of the body.

• MX: Spread cannot be determined.

Questions to ask your doctor

• Do I need additional treatment or tests after surgery?

• How often will I need follow-up imaging or visits?

• What is the likelihood that this tumour could return or spread?

• Are there lifestyle changes I should consider after surgery?

• Should my family consider genetic testing for related conditions?

• What symptoms should prompt me to seek medical attention?