A rare case of rectal inflammatory myofibroblastic tumor mimicking Crohn disease in a child

Inflammatory myofibroblastic tumor is a rare type of mesenchymal tumor, predominantly benign but with intermediate malignant potential. This article presents a clinical case of successful surgical treatment of a child with an extremely rare localization of inflammatory myofibroblastic tumor in the rectum (the fourth reported case worldwide), initially misdiagnosed as Crohn disease. A 4-year-old girl presented with diarrhea, blood, and mucus in stool. Examination revealed ulcerative pancolitis and a rectal mass, initially presumed to be of inflammatory origin. Treatment with mesalazine led to clinical improvement; however, follow-up endoscopy showed no significant regression. Therapy was escalated to topical and systemic budesonide, with a positive response, but symptoms recurred after glucocorticoid withdrawal, including ribbon-like feces and painful defecation. High fecal calprotectin levels persisted throughout the observation period. The condition was interpreted as a stricturing form of Crohn disease. Anti-TNF therapy (infliximab) initially led to clinical improvement, but the rectal mass continued to grow, with progressive anal canal stenosis. A decision was made to perform rectal resection with tumor excision. Histopathological examination confirmed the diagnosis of inflammatory myofibroblastic tumor. Due to the overlapping clinical, laboratory, and imaging features of inflammatory myofibroblastic tumor and Crohn disease, differential diagnosis can be challenging, potentially delaying accurate diagnosis. In this case, a child with an extremely rare localization of an inflammatory myofibroblastic tumor successfully underwent radical surgery, resulting in favorable long-term outcomes.