Postoperative Spindle Cell Nodule: Understanding Your Pathology Report

Section Editor: Trevor Flood MD FRCPC
October 11, 2026

A postoperative spindle cell nodule is a noncancerous, or benign, growth that forms in tissue that is healing after a surgery or procedure. It is made of long, thin cells called spindle cells, which are part of the body’s normal repair process. Most postoperative spindle cell nodules are found in the bladder, the prostate, or the vagina.

Under the microscope, a postoperative spindle cell nodule can look worrying, because the cells are growing quickly and many are dividing. For this reason, the growth can resemble a type of cancer called a sarcoma. However, it is a healing reaction rather than a cancer, and it does not spread to other parts of the body.

This article explains why a postoperative spindle cell nodule forms, how the pathologist tells it apart from cancer, and what your pathology report means for your care.

What causes a postoperative spindle cell nodule?

A postoperative spindle cell nodule forms as part of the healing process after tissue has been cut, scraped, or burned during a procedure. When tissue is injured, cells called myofibroblasts move into the area and multiply to repair it. In a postoperative spindle cell nodule, this repair process is more active than usual and forms a small lump.

The procedures most often linked to a postoperative spindle cell nodule include:

Transurethral resection. A procedure in which tissue is removed from the bladder or prostate through the urethra, such as a TURBT for a bladder tumor.
Surgery of the vagina or cervix. For example, a hysterectomy or a loop electrosurgical excision procedure (LEEP).
Scraping of the uterus. A procedure called curettage, which removes tissue from the lining of the uterus.

A postoperative spindle cell nodule usually appears within a few weeks to about three months after the procedure.

What are the symptoms of a postoperative spindle cell nodule?

Many postoperative spindle cell nodules cause no symptoms and are found during a follow-up examination after surgery. In the bladder, the nodule can cause blood in the urine, which is usually noticed in the weeks after the procedure. A larger nodule can make it harder to start urinating or to empty the bladder completely. In the vagina, it may cause bleeding or be felt as a small lump.

How is the diagnosis made?

The diagnosis of a postoperative spindle cell nodule is made by a pathologist after the growth is removed or sampled with a biopsy. In the bladder, the nodule is usually found during follow-up cystoscopy and removed in the same way as a bladder tumor. Because it can look like a cancer to the urologist or surgeon, examination under the microscope is needed to make the diagnosis.

Under the microscope, the pathologist sees the following features:

Spindle cells. Long, thin cells that are packed closely together and arranged in crossing bundles. The cells can look large, but they do not show the severe abnormalities seen in a sarcoma.
Dividing cells. Many cells may be dividing, which pathologists see as mitotic figures. This reflects the active healing taking place in the tissue. However, abnormal-looking mitotic figures, called atypical mitotic figures, are not seen.
Small blood vessels. Many small blood vessels run through the nodule, often with some bleeding into the tissue around them.
Ulceration and inflammation. The surface may be broken down, forming an ulcer, with immune cells nearby. This is a sign of inflammation and healing at the site of the procedure.

The most important clue for the pathologist is the history of a recent procedure at the same site. Your surgeon or urologist usually includes this information when sending the tissue, and the pathologist may mention it in the report. Some tests on the tissue, described in the next section, help confirm the diagnosis.

Immunohistochemistry

Immunohistochemistry is a test that uses special stains to show which proteins are made by the cells in a postoperative spindle cell nodule. The results help the pathologist confirm that the cells are healing myofibroblasts and rule out cancers that can look similar. The stains used, and how the results are worded, vary between laboratories. Results you may see in your report include:

Smooth muscle actin (SMA). This stain is usually positive in the spindle cells of a postoperative spindle cell nodule. The protein is made by myofibroblasts, the repair cells that form the nodule.
Desmin. This stain is positive in some cases and negative in others. The protein is found in muscle cells and in some myofibroblasts.
Cytokeratins. This stain may be positive in a few of the spindle cells. A positive result does not on its own mean the growth is a carcinoma.
ALK. This stain can be positive or negative in a postoperative spindle cell nodule. A positive ALK result is more typical of a related growth called an inflammatory myofibroblastic tumor, described in the next section.

Not every postoperative spindle cell nodule needs every stain. In a typical case with a clear history of a recent procedure, only a few stains may be needed.

How is a postoperative spindle cell nodule different from other growths?

A postoperative spindle cell nodule belongs to a group of growths made of myofibroblasts, sometimes called myofibroblastic proliferations. The pathologist uses the history, the appearance of the cells, and the stain results to decide which diagnosis fits best. Your report may name one of these related diagnoses instead:

Pseudosarcomatous myofibroblastic proliferation. A growth that looks very similar to a postoperative spindle cell nodule but forms without a recent procedure. Some pathologists consider the two to be closely related forms of the same healing process. Our article on pseudosarcomatous myofibroblastic proliferation describes it in more detail.
Inflammatory myofibroblastic tumor. A true tumor made of myofibroblasts and immune cells, which is often ALK positive. It can come back after removal and rarely spreads. Our article on inflammatory myofibroblastic tumor describes it in more detail.
Leiomyosarcoma. A cancer made of smooth muscle cells that can also form in the bladder or uterus. Its cells look much more abnormal, and it often shows atypical mitotic figures and areas of dead tissue. Our article on leiomyosarcoma describes this cancer and how it is treated.
Sarcomatoid carcinoma. A cancer in which some cells have become long and thin like spindle cells. In the bladder, it often occurs together with urothelial carcinoma, and its cells look very abnormal.

Margins

When a postoperative spindle cell nodule is removed, the pathologist may comment on whether the growth reaches the edges of the tissue sample, called the margins. For a bladder nodule removed through the urethra, the tissue comes out in small pieces, so margins usually cannot be assessed. Because the nodule is not a cancer, a growth that reaches the margin does not usually need more surgery.

Can a postoperative spindle cell nodule come back?

A postoperative spindle cell nodule usually does not come back after it is removed. It does not turn into cancer, and it does not spread to lymph nodes or other parts of the body. If a similar growth appears again, it is usually examined again to confirm the diagnosis.

What happens after the diagnosis?

After a diagnosis of a postoperative spindle cell nodule, treatment is usually simple, because the growth is benign. Chemotherapy and radiation are not needed for this healing reaction. Your doctor will decide on next steps based on where the nodule is, its size, and whether it is causing symptoms.

No further treatment. If the nodule was removed or sampled and is not causing symptoms, often no further treatment is needed.
Removal. A nodule that causes bleeding or blocks the flow of urine can be removed in a short procedure.
Follow-up for the original condition. If you had surgery for a bladder or other cancer, your regular follow-up for that cancer continues. The postoperative spindle cell nodule does not change that cancer’s treatment or outlook.

Questions to ask your doctor

Was the postoperative spindle cell nodule related to my recent procedure?
How sure is the pathologist that this is not a cancer?
Which stains were done, and what did they show?
Was the ALK stain positive or negative, and does it matter for me?
Could this be a pseudosarcomatous myofibroblastic proliferation or an inflammatory myofibroblastic tumor instead?
Was the nodule removed completely, or was only a sample taken?
Do I need any further treatment for the nodule?
Will the nodule affect follow-up for my original condition?
What symptoms should make me contact you?