EP1052 - Pseudosarcomatous Myofibroblastic Proliferation of the Rectum; a Case Report

Monday, May 11, 2026

4:41 PM - 4:46 PM ET

ePoster Presenter(s)

RS

Rachel B. Scott, DO (she/her/hers)

Chief of Colon and Rectal Surgery St. Francis Hospital
Colon and Rectal Surgeons of Greater Hartford
St. Francis Hospital and Medical Center
West Hartford, CT, United States

Disclosure information not submitted.

Author(s)

MZ

Muhammad H. Zafar, MD

PGY3 General surgery resident
University of Connecticut School of Medicine
Hartford, Connecticut, United States

Disclosure information not submitted.
AR

Andrew C. Raissis, MD

Colorectal Surgeon faculty
Andrew Raissis
West Hartford, Connecticut, United States

Disclosure information not submitted.
DM

Daniel Mullins, M.D.

Colon and Rectal Surgeon
Saint Francis Hospital
Hartford, Connecticut, United States

Disclosure information not submitted.
JC

Jonathan Chang, MD

Staff Surgeon
Colon and Rectal Surgeons of Greater Hartford
Bloomfield, Connecticut, United States

Disclosure information not submitted.
RL

Robert T. Lewis, MD (he/him/his)

Program Director, Saint Francis Hospital
Colon and Rectal Surgeons of Greater Hartford
Saint Francis Hospital and Medical Center
Bloomfield, CT, United States

All of the relevant financial relationships listed below have been mitigated.
This individual has no financial relationships with ineligible companies.

Senior Author(s)

Vanessa Marie Baratta, MD, MHS

Colon and Rectal Surgeon
Colon and Rectal Surgeons of Greater Hartford
Ivoryton, Connecticut, United States

All of the relevant financial relationships listed below have been mitigated.
This individual has no financial relationships with ineligible companies.

All of the relevant financial relationships listed below have been mitigated.

Robert T. Lewis, MD: This individual has no financial relationships with ineligible companies.

Vanessa Marie Baratta, MD, MHS: This individual has no financial relationships with ineligible companies.

Purpose/Background: Pseudosarcomatous myofibroblastic proliferation (PMP) is a rare disease process of unknown etiology and pathogenesis. According to the latest World Health Organization (WHO) classification, a PMP is a benign tumor with malignant potential derived from fibroblasts and myofibroblasts. It is mainly reported in the urinary system while other sites where PMPs may occur include the head, neck, pelvic cavity, retroperitoneum, and abdomen.

Methods/Interventions: A 65-year-old nonverbal male presented to the clinic from a group home with the primary complaint of having bright red blood per rectum for the past 6 months. Otherwise, his accompanying aide reported him having a good appetite, regular bowel movements, and no weight loss. A colonoscopy had already been performed a year prior to his presentation during which a rectal lesion had been identified. On pathology, the neoplasm was positive for ALK and desmin, weakly positive for actin, and negative for S100. After discussion with expert pathologists at outside institution, a final diagnosis of PMP was reached. On DRE in clinic, a fixed, firm lesion was palpable around 5 cm from the anorectal verge which seemed to occupy ~25% of circumference. The patient subsequently underwent an MRI abdomen/ pelvis which demonstrated a polypoid, non-mucinous, 3.6 cm left anterior low/ mid rectal mass extending to the level of puborectalis. The tumor was deemed to be T1/ early T2 since there was no definite extension beyond muscularis propria or definitive involvement of anal sphincter. The case was presented at the institutional tumor board and the group consensus was to manage the lesion surgically. Therefore, the patient underwent an open trans anal excision of the rectal lesion which was removed in its entirety.

Results/Outcomes: Patient's postoperative course was complicated by acute heart failure and left pleural effusion development requiring thoracentesis. Once his medical issues were managed, he was discharged back to his group home a week after surgery. Final pathology demonstrated PMT with the tumor invading through muscularis propria into perirectal tissue. However, there was tumor noted to be on inked margin. For his postoperative follow up, routine surveillance with flexible sigmoidoscopy and a CT abdomen pelvis has been recommended. At the 6-month flexible sigmoidoscopy, we plan of taking a biopsy of the scar to assess for any residual tumor deposits.

Conclusion/Discussion: Most reports of PMPs are in the urinary tract, and the only reports of a PMP in the digestive field have been in the gallbladder and appendix. To our knowledge, our case is the first to be reported in the lower gastrointestinal tract. The final diagnosis of PMP is challenging and can only be confirmed by the results of postoperative histopathologic and immunohistochemical examinations. IMT is a similar disease to PMP; the definitions of PMP and IMT remain controversial because their potential for malignancy is unclear. Therefore, there are no clear guidelines for management of inflammatory pseudotumors. Surgery remains the mainstay of treatment. It is unclear whether a PMP is a genuine tumor, a reactive lesion, or even a proliferative mesenchymal lesion. Therefore, further research and postoperative surveillance are needed to guide

establishment of correct diagnostic strategies and management guidelines for these lesions.