by Jason Wasserman MD PhD FRCPC and Trevor Flood MD FRCPC
August 20, 2024
A postoperative spindle cell nodule (PSCN) is a noncancerous growth that develops after surgical manipulation. Other names for this condition include pseudosarcomatous myofibroblastic proliferation and pseudosarcomatous myofibroblastic neoplasm.
Most postoperative spindle cell nodules are found in the urinary tract, specifically the bladder and the prostate gland. However, these growths can also be found in the cervix, uterus, and skin.
A postoperative spindle cell nodule is caused by surgical manipulation. For example, in the urinary tract, this growth commonly develops after a procedure called transurethral resection of a bladder tumour (TURBT). A similar growth in the cervix or uterus may develop after a loop electrosurgical excision procedure (LEEP) or curettage.
Most postoperative spindle cell nodules do not cause any symptoms, and the growth is discovered incidentally, for example, when the bladder or prostate gland is examined. Large nodules may cause symptoms such as bloody urine and difficulty initiating urination or fully emptying the bladder.
This diagnosis can be made after the growth is removed and a pathologist examines the tissue under the microscope.
When examined under the microscope, the growth is made up of spindle cells – cells that are longer than wide. The spindle cells are arranged in intersecting bundles described as fascicles or fascicular. Mitotic figures (cells dividing to create new cells) may be seen, although no atypical mitotic figures should be identified. A type of injury called an ulcer may be seen at the surface of the tissue, and a combination of acute and chronic inflammatory cells are usually associated with the ulcer. Small blood vessels may be seen in the connective tissue surrounding the spindle cells.
Pathologists often perform a immunohistochemistry (IHC) test to confirm the diagnosis. This test helps distinguish a postoperative spindle cell nodule from other types of growths that can look similar under the microscope. When IHC is performed, the spindle cells are typically positive for muscle markers such as smooth muscle antigen (SMA) and desmin. The spindle cells may also be positive for ALK protein.