Viscus perforation as an initial presentation of plexiform fibromyxoma: A case report and review of the literature.

INTRODUCTION: Plexiform fibromyxoma (PF) is a rare benign mesenchymal neoplasm of stomach recognized by the WHO. The tumor often arises in the antrum and pyloric region of the stomach. Morphologically, PF tumors display bland spindle cells in myxoid or fibromyxoid stroma and can be misdiagnosed as gastrointestinal stromal tumor (GIST). PRESENTATION OF CASE: A-21-year old female presented to emergency department with peritonitis due gastric tumor leading to gastric perforation and pus collection in the abdomen. Partial gastrectomy was performed. Histopathology, immunohistochemical (IHC) and fluorescent in-situ hybridization assessment of the specimen confirmed the diagnosis of PF. One year postoperative, the patient remains symptoms free. CLINICAL DISCUSSION: A great majority of gastric mesenchymal tumors are GIST. Histopathologically, PF tumors display a multinodular and plexiform architecture with arborizing vasculature. Cytologically these tumors show bland spindle cells in myxoid or fibromyxoid stroma with a rare or no mitotic figures. Thus, PF may easily be under recognized or misinterpreted without the pathologists' knowledge of this entity. Misinterpreting PF as GIST can lead to inappropriate treatment including unnecessary surgery and/or chemotherapy, which is an expensive. Recommended treatment is surgical excision. Metastases and recurrence following complete excision have not been described. This case highlights unexpected presentation in a young female where other competing diagnoses were more plausible before considering PF diagnosis which could not have been established without advanced diagnostic techniques. CONCLUSION: PF is a rare mesenchymal tumor with nonspecific clinical characteristics. It is principally located in the gastric antrum and prepyloric regions, however other parts of the body may be affected. PF tumors should be separated from GIST, nerve sheath tumors, and other fibromyxoid neoplasms. The worth in writing lies in epidemiological custodianship for such a unique presentation of a rare gastric neoplasm.