Collecting Duct Carcinoma of the Kidney: Understanding Your Pathology Report

Section Editor: Trevor Flood MD FRCPC
October 28, 2026

Collecting duct carcinoma is a rare type of kidney cancer that starts in the collecting ducts. These are small tubes deep in the center of the kidney that carry urine toward the renal pelvis. It is also called collecting duct renal cell carcinoma or carcinoma of the collecting ducts of Bellini. Collecting duct carcinoma tends to grow quickly and to spread early. Many people already have cancer in lymph nodes or other organs when it is found.

This article explains how pathologists diagnose collecting duct carcinoma and why they must first rule out several other cancers. It also explains the grade, stage, margins, and lymph node results in your pathology report, and the treatments your care team may discuss.

Who gets collecting duct carcinoma?

Collecting duct carcinoma accounts for about 1 in every 100 kidney cancers. It is about twice as common in men as in women, for reasons not yet understood. The average age at diagnosis is in the mid to late 50s, but it has been reported in people from childhood to their 80s.

What causes collecting duct carcinoma?

The cause of collecting duct carcinoma is not known, and no clear risk factors have been identified. Unlike clear cell renal cell carcinoma, it does not involve VHL gene changes or loss of part of chromosome 3. The tumor cells often have changes in genes such as NF2, SETD2, and CDKN2A, but no single change defines this cancer.

What are the symptoms of collecting duct carcinoma?

About two out of three people with collecting duct carcinoma have symptoms when it is found. Common symptoms include:

Blood in the urine. The blood may be visible or only detected on a urine test.
Pain. Pain may be felt in the side, back, or abdomen.
General symptoms. Weight loss and tiredness are common when the cancer has spread.
A lump. A mass may be felt in the side of the abdomen.

How is the diagnosis made?

Collecting duct carcinoma is usually first seen as a mass in the center of the kidney on a CT scan or MRI. Tissue for diagnosis comes from a needle biopsy of the mass or from surgery to remove the kidney. A pathologist then examines the tissue under the microscope to make the diagnosis. Imaging of the chest, abdomen, and pelvis looks for spread to lymph nodes and other organs.

Under the microscope, the tumor grows into the surrounding kidney in an irregular, infiltrative way. The cancer cells form small tubes and cords surrounded by dense, scar-like tissue (desmoplasia) and often by inflammation. The cells are large and very abnormal, and many are dividing, and areas of dead tumor, called tumor necrosis, are common.

Collecting duct carcinoma is what pathologists call a diagnosis of exclusion. This means the pathologist makes it only after ruling out other cancers that can look the same. These look-alikes include:

Urothelial carcinoma, a cancer that starts in the lining of the renal pelvis.
Fumarate hydratase-deficient renal cell carcinoma, which can be inherited.
Renal medullary carcinoma, which mainly affects young people with sickle cell trait.
Cancer that has spread to the kidney from another organ.

Special stains help rule these out, as described in the next section.

Immunohistochemistry

Immunohistochemistry uses antibodies to show which proteins cells make. In collecting duct carcinoma, pathologists use immunohistochemistry to confirm that the tumor started in the kidney and to rule out its look-alikes. The stains used vary between laboratories, but typical results include:

PAX8. Positive, which supports a tumor that started in the kidney.
High molecular weight keratin (34βE12) and CK7. Usually positive, as in the normal cells lining the collecting ducts.
GATA3 and p63. Negative in this tumor. These stains are usually positive in urothelial carcinoma, so a negative result helps rule it out.
INI1 (SMARCB1). Retained, meaning the protein is still present in the tumor cells. Loss of INI1 would point instead to renal medullary carcinoma.
Fumarate hydratase (FH). Retained, meaning the protein is still present in the tumor cells. Loss of FH would point instead to fumarate hydratase-deficient renal cell carcinoma, which can be linked to an inherited condition.

Not every tumor needs all of these stains, and the exact panel depends on the laboratory. The pathologist interprets the results together with how the tumor looks and where it is in the kidney.

Histologic grade

Most kidney cancers are given a WHO/ISUP grade from 1 to 4. Collecting duct carcinoma is not graded this way. Pathologists already consider it a high-grade cancer, so a grade number would not add useful information. The College of American Pathologists (CAP) kidney protocol, version 4.2.0.0 (2024), states that grading is unnecessary for this tumor. Your report may state that grading is not applicable, and this is expected.

Sarcomatoid and rhabdoid features and tumor necrosis

The CAP kidney protocol asks the pathologist to report certain features in every kidney cancer, including collecting duct carcinoma. Your report may describe any of the following features:

Sarcomatoid features. Part of the tumor is made of long, spindle-shaped cells. This has been linked to a higher risk of death in collecting duct carcinoma.
Rhabdoid features. Part of the tumor is made of large, round cells with pink cytoplasm. Rhabdoid features are also an unfavorable finding in kidney cancer.
Tumor necrosis. The report states whether areas of dead tumor are present or not identified.

Lymphovascular invasion

In collecting duct carcinoma, lymphovascular invasion means cancer cells are seen inside a lymphatic channel or blood vessel. These vessels can carry cancer cells to lymph nodes and other organs. Lymphovascular invasion is common in collecting duct carcinoma, and the CAP protocol requires reporting it as present or not identified.

Surgical margins

A margin is the cut edge of tissue removed during surgery for collecting duct carcinoma. The margins checked include the fat around the kidney, the renal vein, and the ureter. Following the CAP kidney protocol, your report will describe the margins in one of these ways:

Negative margin. No cancer cells are seen at any cut edge, which suggests the tumor was completely removed. Some reports also give the distance to the closest margin.
Positive margin. Cancer cells are present at a cut edge, so that some cancer may remain in the body. This may affect the treatment your care team discusses after surgery.

Lymph nodes

Collecting duct carcinoma spreads to lymph nodes more often than most kidney cancers. In one large study, about 4 in 10 people had cancer in nearby lymph nodes. Lymph nodes near the kidney are therefore often removed during surgery and checked for cancer cells. Your report will include the number of nodes examined and how many contain cancer. Some reports also state whether extranodal extension is present. This means cancer cells have broken through the lymph node’s outer capsule into surrounding tissue.

Biomarker and molecular testing

For most people with collecting duct carcinoma, there are currently no biomarker tests that guide the choice of a specific targeted drug. The stains used to confirm the diagnosis, described above, are diagnostic tests rather than treatment-directing biomarkers. When cancer has spread, next-generation sequencing may be used to look for changes that could make a person eligible for a clinical trial. One example is loss of the CDKN2A gene, which has been linked to shorter survival and is being studied as a treatment target. Your oncologist can tell you whether molecular profiling is appropriate in your situation. Our Biomarkers and Genetic Testing section has more information about these tests.

Pathologic stage (pTNM)

The pathologic stage of collecting duct carcinoma describes the size and extent of the tumor and whether it has spread to lymph nodes. It uses the TNM system from the AJCC Cancer Staging Manual, 8th edition, which is still current for kidney cancer. The M category, for spread to distant organs, is usually decided by imaging rather than by the pathologist.

Tumor stage (pT)

pT1a. The tumor is 4 cm or smaller and limited to the kidney.
pT1b. The tumor is larger than 4 cm but no larger than 7 cm, and limited to the kidney.
pT2a. The tumor is larger than 7 cm but no larger than 10 cm, and limited to the kidney.
pT2b. The tumor is larger than 10 cm and limited to the kidney.
pT3a. The tumor has grown into the renal vein or its branches, the renal pelvis, or the fat around the kidney or its center.
pT3b. The tumor has grown into the vena cava, the large vein that returns blood to the heart, below the diaphragm.
pT3c. The tumor has grown into the vena cava above the diaphragm, or into its wall.
pT4. The tumor has grown through Gerota’s fascia, the outer covering around the kidney, or directly into the adrenal gland on the same side.

Collecting duct carcinoma usually starts in the center of the kidney. Growth into the renal pelvis or the fat in the center of the kidney places a tumor in the pT3a category, even when the tumor is small.

Nodal stage (pN)

pN0. The pathologist found no cancer in any of the lymph nodes examined.
pN1. Cancer was found in one or more nearby lymph nodes.
pNX. Lymph nodes were not removed or could not be assessed; some reports list “pN not assigned” instead.

What is the prognosis?

The prognosis for collecting duct carcinoma is poorer than for the more common types of kidney cancer, mainly because it is often found after it has spread. About 4 in 10 people have distant metastases at diagnosis. Published studies report a median overall survival of about 1 year. About 1 in 4 people are alive 5 years after diagnosis.

Outcomes for collecting duct carcinoma depend strongly on the stage. A large United States study measured 3-year relative survival, which compares people with the cancer to people of the same age without it. It was about 93 in 100 when the cancer was confined to the kidney. It fell to about 45 in 100 with spread to nearby tissues or lymph nodes, and about 6 in 100 with spread to distant organs. Features linked with a worse outcome include:

Spread to distant organs. This is the most important factor, and it is present in many people at diagnosis.
Cancer in the lymph nodes. Nodal spread is associated with a higher risk of the cancer coming back.
Sarcomatoid features. These have been linked to a higher risk of death in this cancer.
No surgery to remove the kidney. In studies, people who had surgery lived longer, although people well enough for surgery may differ in other ways.

What happens after the diagnosis?

After diagnosing collecting duct carcinoma, the next steps depend mainly on the stage, lymph node results, and your general health. Because this cancer is rare, care is often planned at a specialized center, and clinical trials are an important option. Treatment options your care team may discuss include:

Radical nephrectomy. Surgery to remove the whole kidney, often with the nearby lymph nodes. This is the main treatment when the cancer has not spread to distant organs.
Chemotherapy. Gemcitabine combined with cisplatin or carboplatin has been used for cancer that has spread. In a small trial of 23 people, the cancer shrank in about 1 in 4.
Targeted therapy. Cabozantinib, a drug used for other kidney cancers, was studied in a small trial of 23 people with collecting duct carcinoma. The cancer shrank in about 1 in 3 of these people.
Immunotherapy. Drugs such as nivolumab have helped some people in individual case reports. Their role in collecting duct carcinoma is still being studied in clinical trials.
Clinical trials. Several trials for rare kidney cancers include people with collecting duct carcinoma. Your oncologist can tell you whether any are open to you.

No drug has yet been shown in a large trial to work best for collecting duct carcinoma. Whether treatment after surgery lowers the chance of the cancer coming back is not known. Follow-up usually includes regular CT scans and checks of your kidney function after a kidney is removed.

Questions to ask your doctor

How certain is the diagnosis of collecting duct carcinoma?
Which special stains were done, and were urothelial carcinoma and other kidney cancers ruled out?
Were the FH and INI1 stains normal?
Should a specialist kidney pathologist review my tissue?
Were sarcomatoid or rhabdoid features found?
What is the pathologic stage (pT and pN)?
Were the margins negative?
How many lymph nodes were removed, and did any contain cancer?
Has the cancer spread to other parts of my body?
Would next-generation sequencing of my tumor be useful?
What treatments are available, and what are their benefits and risks?
Are there clinical trials I could join?
How often will I need scans, and for how long?