Misdiagnosis of Gastric Plexiform Fibromyxoma as Gastrointestinal Stromal Tumor: A Case Report

Plexiform fibromyxoma is a rare primary mesenchymal tumor of the gastrointestinal tract, first reported by Takahashi in 2007 and officially recognized as a subtype of gastric mesenchymal tumor by the World Health Organization (WHO) (Classification of Tumors of the Digestive System, 4th ed.) in 2010. The disease is prevalent in the gastric sinus and pyloric region, and common clinical manifestations include gastrointestinal bleeding, ulceration and secondary anemia. Due to the extremely low incidence of PF and the lack of specificity in imaging, it is easily misdiagnosed as GIST, smooth muscle tumor, nerve sheath tumor, and sclerofibromatosis before surgery. Less than 200 cases of PF have been reported in the literature, and there is a lack of systematic analysis of cases with atypical clinical manifestations (e.g., acute attacks, severe anemia, etc.). We report a case of a 31-year-old female patient with acute onset of severe anemia due to bleeding from a ruptured tumor. CT of the upper abdomen suggested cystic solid occupancy in the gastric antrum, and the possibility of gastrointestinal mesenchymal tumor was considered. The patient underwent tumor resection and postoperative pathology confirmed the diagnosis of tufted fibromucinous tumor. The patient recovered well after surgery and is currently undergoing long-term follow-up. This case highlights the diagnostic challenges associated with PF, particularly when presenting atypically, and underscores the importance of multidisciplinary evaluation to avoid misdiagnosis and ensure timely management.