Introduction: Inflammatory myofibroblastic tumors (IMTs) are uncommon mesenchymal lesions classified by WHO as neoplasms of uncertain behavior. Morphologically, IMTs are composed of proliferating spindled myofibroblastic cells accompanied by a marked - usually chronic - inflammatory infiltrate. The etiology is unknown, but several theories have been suggested, including an association with Wilms' tumor. IMTs are rarely diagnosed in adults and have been reported in various organs. IMTs are considered benign but with a potential to recur at their primary site. Case report: A 44-year-old female experienced intermittent severe abdominal pain, loose stools and a visible abdominal bulge. In early childhood the patient had been treated for a Wilms' tumor. At admission Meckel's diverticulitis was suspected, but during surgery a tumor in the terminal ileum, creating a conglomerate of small intestinal loops, was observed and completely resected. The pathology report characterized the tumor as a histologically benign inflammatory myofibroblastic tumor. Postoperatively, the patient experienced several complications including an anastomotic leakage and subsequent formation of an abscess and transcutaneous fistula. Discussion: IMTs rarely arise in the small intestine, and to our knowledge the manifestation of a small intestine conglomerate has not been described previously. Making the diagnosis is difficult, and numerous differential diagnoses were possible in this case. Approximately 8-25% of IMTs in the gastrointestinal tract recur locally. Complete surgical resection is the treatment of choice, and re-excision is the preferred therapy for local recurrence. To our knowledge, no guidelines concerning follow-ups are available. Conclusion: IMTs in the terminal ileum can mimic Meckel's diverticulitis and present with symptoms of obstructive ileus due to the formation of a conglomerate of small intestinal loops. Furthermore, IMTs should be considered as a diagnostic possibility in patients with a past medical history of Wilms' tumor.