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Adult gastric inflammatory myofibroblastic tumors (IMT) are rare mesenchymal neoplasms that often mimic gastrointestinal stromal tumors (GIST). This systematic review with pooled individual patient data aimed to define their clinical presentation, diagnostic work-up, and surgical management. Electronic databases (PubMed/MEDLINE, Embase, Scopus, Cochrane Library) were searched for adult (≥18 years) cases of histologically confirmed gastric IMT. Individual patient data on demographics, tumor characteristics, treatment, and outcomes were extracted from eligible case reports and series. Continuous variables were summarized as means with standard deviations and categorical variables as proportions with 95% confidence intervals, with prespecified comparisons by tumor location and surgical approach. Thirty-one patients were identified, with a female predominance and a mean age of 47.7 years. Most were symptomatic, presenting with abdominal pain or upper gastrointestinal bleeding/anemia. Tumors most frequently involved the middle third of the stomach and showed wide size variability. Distal tumors were larger and predominantly associated with pain, whereas proximal tumors more often presented with hemorrhage and less pain, suggesting distinct location-dependent clinical phenotypes. Surgical resection was the mainstay of treatment. Stomach-preserving resections were feasible in most cases, and minimally invasive surgery (MIS) was increasingly used for smaller, well-circumscribed lesions, while larger or locally invasive tumors more often required open major gastrectomy. Preoperative EUS-guided biopsy with immunohistochemistry, including ALK-1, is critical to avoid misdiagnosis. Complete surgical resection offers excellent short-to mid-term outcomes, and MIS stomach-preserving techniques appear safe for tumors under 5 cm when negative margins can be achieved.