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World J Gastrointest Oncol. May 15, 2021; 13(5): 409-423
Published online May 15, 2021. doi: 10.4251/wjgo.v13.i5.409
Plexiform fibromyxoma: Review of rare mesenchymal gastric neoplasm and its differential diagnosis
Mustafa Erdem Arslan, Hua Li, Zhiyan Fu, Timothy A Jennings, Hwajeong Lee
Mustafa Erdem Arslan, Hua Li, Zhiyan Fu, Timothy A Jennings, Hwajeong Lee, Pathology and Laboratory Medicine, Albany Medical Center, Albany, NY 12208, United States
Author contributions: All authors have contributed to the manuscript and agree with the final version of the manuscript; Arslan ME performed the literature search, collected the data, and wrote the manuscript draft; Li H and Fu Z helped with data collection, literature search, and manuscript review; Jennings TA helped with manuscript review and critical revision; Lee H performed design and conceptualization, study supervision, manuscript editing, and finalization.
Conflict-of-interest statement: The authors declare no conflict of interest for this article.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Hwajeong Lee, MD, Associate Professor, Pathology and Laboratory Medicine, Albany Medical Center, 43 New Scotland Ave, Albany, NY 12208, United States. leeh5@amc.edu
Received: February 19, 2021
Peer-review started: February 19, 2021
First decision: March 15, 2021
Revised: March 22, 2021
Accepted: April 26, 2021
Article in press: April 26, 2021
Published online: May 15, 2021
Abstract

Plexiform fibromyxoma (PF) is a very rare mesenchymal neoplasm of the stomach that was first described in 2007 and was officially recognized as a subtype of gastric mesenchymal neoplasm by World Health Organization (WHO) in 2010. Histologically, PF is characterized by a plexiform growth of bland spindle to ovoid cells embedded in a myxoid stroma that is rich in small vessels. The lesion is usually paucicellular. While mucosal and vascular invasion have been documented, no metastasis or malignant transformation has been reported. Its pathogenesis is largely unknown and defining molecular alterations are not currently available. There are other mesenchymal tumors arising in the gastrointestinal tract that need to be differentiated from PF given their differing biologic behaviors and malignant potential. Histologic mimics with spindle cells include gastrointestinal stromal tumor, smooth muscle tumor, and nerve sheath tumor. Histologic mimics with myxoid stroma include myxoma and aggressive angiomyxoma. Molecular alterations that have been described in a subset of PF may be seen in gastroblastoma and malignant epithelioid tumor with glioma-associated oncogene homologue 1 (GLI1) rearrangement. The recent increase in publications on PF reflects growing recognition of this entity with expansion of clinical and pathologic findings in these cases. Herein we provide a review of PF in comparison to other mesenchymal tumors with histologic and molecular resemblance to raise the awareness of this enigmatic neoplasm. Also, we highlight the challenges pathologists face when the sample is small, or such rare entity is encountered intraoperatively.

Keywords: Plexiform, Fibromyxoma, Gastrointestinal, Mesenchymal, Neoplasm, Stomach

Core Tip: Plexiform fibromyxoma (PF) is a rare mesenchymal tumor of the stomach. Due to its rarity, the pathogenesis and molecular alterations of PF are largely unknown. The incidence of the tumor seems to be increasing probably due to a growing awareness of this entity. Histologic mimics of PF include gastrointestinal stromal tumor, smooth muscle tumor, nerve sheath tumor, myxoma and aggressive angiomyxoma. Molecular mimics of PF include gastroblastoma and malignant epithelioid tumor with glioma-associated oncogene homologue 1 (GLI1) rearrangement. Surgical removal is the current mainstay of treatment.