P1909 - The First Reported Case of a Pseudosarcomatous Stromal Tumor: A Unique Benign Ampullary Tumor

Award: Presidential Poster Award

Penelope Quiles, ¹, Jacob C. Jones, DO², John G. Quiles, MD², Jerome C. Edelson, MD^2
1Washington and Lee University, San Antonio, TX; ²Brooke Army Medical Center, San Antonio, TX

Introduction: Pseudosarcomatous stromal proliferation is a rare, benign lesion usually found in submucosal stroma of the bladder, with few reports in the GI tract. Treatments include surgical resection, endoscopic resection, laser ablation, photodynamic therapy, and/or chemotherapy. Here, we present a case of pseudosarcomatous stromal proliferation involving the ampullary and duodenal mucosa.

Case Description/Methods: A 61-year-old male with a history of prostate and carotid paraganglioma and metabolic associated liver disease was incidentally found to have a duodenal mass on MRI obtained to assess liver stiffness. The patient was asymptomatic and was referred for endoscopic visualization. A 20 mm x 17 mm, friable, fungating, and ulcerated non-obstructing ampullary mass was discovered, suggestive of ampullary adenocarcinoma. Biopsies were obtained and demonstrated reactive epithelial with stromal changes. Multidisciplinary discussion was performed including Surgical Oncology, with recommendations for EUS with FNB, which again demonstrated stromal proliferation and reactive changes. Labs to include CA 19-9, CA-125, CEA, IgG4, and liver function tests were normal. The patient subsequently underwent endoscopic papillectomy which was successful with R0 resection. Pathology demonstrated substantial fibroblastic/myofibroblastic stromal proliferation involving the ampullary and duodenal mucosa with marked reactive epithelial changes and gastric mucin cell metaplasia, consistent with pseudosarcomatous stromal changes. There was no evidence of any malignancy, including sarcomatoid prostate carcinoma or paraganglioma.

Discussion: This is the first known case of pseudosarcomatous stromal proliferation involving the ampullary and duodenal mucosa. Pseudosarcomatous stromal proliferation is typically found in the urogenital tract, though few have been reported within GI tract. Given the patients benign presentation, surgical management was deferred in favor of endoscopic papillectomy. This pseudosarcomatous stromal proliferation and its treatment is unprecedented, therefore, should serve as an example for similar cases.



Disclosures:


Penelope Quiles, ¹, Jacob C. Jones, DO², John G. Quiles, MD², Jerome C. Edelson, MD². P1909 - The First Reported Case of a Pseudosarcomatous Stromal Tumor: A Unique Benign Ampullary Tumor, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.