Postoperative spindle cell nodule

by Jason Wasserman MD PhD FRCPC and Trevor Flood MD FRCPC
June 11, 2025

A postoperative spindle cell nodule is a non-cancerous growth that can develop after certain surgical procedures or manipulations. Although it may sometimes be mistaken for cancer under a microscope, this condition is entirely benign (non-cancerous). Other names for this condition include pseudosarcomatous myofibroblastic proliferation and pseudosarcomatous myofibroblastic neoplasm.

Where are postoperative spindle cell nodules typically found?

Postoperative spindle cell nodules most commonly occur in the urinary tract, particularly in the bladder and prostate gland. However, these growths can also develop in other locations, such as the cervix, uterus, and occasionally on the skin.

What causes postoperative spindle cell nodules?

Postoperative spindle cell nodules develop as a reaction to surgical procedures or physical manipulation of tissues. For instance, in the urinary tract, this growth commonly forms following a procedure known as a transurethral resection of a bladder tumour (TURBT). Similarly, procedures performed on the cervix or uterus, such as a loop electrosurgical excision procedure (LEEP) or a curettage, can lead to the formation of these nodules. Essentially, the body responds to surgical injury or irritation by producing these non-cancerous growths as part of the healing process.

What are the symptoms of a postoperative spindle cell nodule?

Most people with postoperative spindle cell nodules do not experience noticeable symptoms. Often, the nodule is discovered incidentally during a routine medical exam or follow-up procedure.

However, if the nodule grows larger, it may cause symptoms such as:

• Blood in the urine (hematuria).

• Difficulty initiating urination.

• Trouble completely emptying the bladder.

These symptoms typically occur if the growth becomes large enough to interfere with normal bladder function.

How is postoperative spindle cell nodule diagnosed?

A definitive diagnosis of a postoperative spindle cell nodule is made by a pathologist who examines the removed tissue under a microscope. Usually, this happens after the nodule is surgically removed or biopsied. Pathologists perform careful microscopic evaluations to ensure the growth is accurately identified and distinguished from other potentially harmful conditions.

Microscopic features of postoperative spindle cell nodule

When viewed under the microscope, a postoperative spindle cell nodule has several distinctive features:

• Spindle cells: The nodule is composed mainly of elongated cells known as spindle cells. These cells are longer than they are wide, resembling a spindle shape.

• Fascicles: The spindle cells often arrange themselves into intersecting bundles, known as fascicles, giving the tissue a characteristic appearance.

• Mitotic figures: Cells that are actively dividing (mitotic figures) might be visible, reflecting normal cell turnover due to healing and regeneration. Importantly, pathologists should not see any abnormal or atypical mitotic figures.

• Ulceration and inflammation: An injury known as an ulcer may be present on the tissue’s surface. Ulcers typically occur in conjunction with inflammation, featuring both acute (recent) and chronic (long-term) inflammatory cells.

• Blood vessels: Small blood vessels often appear within the connective tissue surrounding the spindle cells, reflecting increased blood supply to support healing.

What other tests may be performed to confirm this diagnosis?

To confirm the diagnosis, pathologists frequently perform an additional specialized test called immunohistochemistry (IHC). This test utilizes specific antibodies to identify particular proteins in cells, enabling the clear differentiation of postoperative spindle cell nodules from other similar-looking conditions.

When immunohistochemistry is performed on a postoperative spindle cell nodule, the spindle cells typically test positive for markers associated with muscle tissue, including smooth muscle actin (SMA) and desmin.

Additionally, spindle cells sometimes express a protein known as ALK (anaplastic lymphoma kinase). These results enable pathologists to confidently establish the diagnosis of postoperative spindle cell nodule and rule out conditions that could mimic its appearance, such as certain types of cancer.

How is a postoperative spindle cell nodule treated?

In most cases, no further treatment beyond removing the irritating factor is necessary. If symptoms occur or the growth interferes with organ function, your doctor may recommend surgical removal of the nodule. Since these nodules are benign, they do not require chemotherapy or radiation therapy. Following removal, postoperative spindle cell nodules typically do not recur, especially once the source of irritation has been addressed.

Follow-up care

Your doctor may recommend regular follow-up visits, especially if you have ongoing symptoms or are at risk of repeated irritation to the affected area. Follow-up care can help ensure proper healing and monitor for any recurrence or complications.

Questions to ask your doctor

• What specifically caused my postoperative spindle cell nodule?

• Will I require treatment for this growth, or will it resolve on its own?

• Could this nodule recur after removal?

• What symptoms should I look out for that might indicate a recurrence or complication?

• Should I schedule regular follow-up appointments or imaging tests?

• Are there steps I can take to reduce the risk of developing this condition again?