Exophytic Gastric Mass Posing a Diagnostic Dilemma: A Case of Mesenteric Fibromatosis

Mesenteric fibromatosis (MF) and gastrointestinal stromal tumor (GIST) are distinct types of lesions that are often mistaken for one another. Fibromatosis of the stomach is a rare condition that can be misdiagnosed as GIST, with MF accounting for only 0.3% of all tumors. Due to its rarity, accurately identifying and appropriately treating this condition poses a significant challenge. Here, we report a case of a 45-year-old female who presented with multiple episodes of vomiting after food intake. Initial radiological investigations suggested a diagnosis of GIST. However, histopathological examination of the surgical excision specimen confirmed fibromatosis with a keloid pattern. Beta-catenin is a key marker for MF; although immunohistochemistry markers were negative for beta-catenin in this case, it is important to note that beta-catenin positivity is observed in only 70-80% of cases. Differentiating these two distinct tumors can be challenging due to potential overlaps in clinical presentation, macroscopic appearance, and even histological features.