Pediatric Mesenteric Inflammatory Myofibroblastic Tumor Presenting as a Diagnostic Challenge: A Case Report and Literature Review.

Background: Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal neoplasm of intermediate malignant potential that predominantly affects children and young adults. Although pulmonary involvement is most frequently reported, mesenteric IMT is uncommon in pediatric patients. Its diagnosis remains challenging due to nonspecific clinical manifestations and significant radiologic and histopathologic overlap with other mesenchymal tumors. Case Presentation: We describe the case of a 5-year-old girl who presented with a three-month history of progressive abdominal distension, anorexia, and weight loss. Radiologic evaluation revealed a calcified mesenteric mass initially suggestive of a calcified fibrous tumor. The patient subsequently underwent exploratory laparotomy with complete surgical excision of the lesion. Histopathologic examination, supported by immunohistochemical analysis, established the diagnosis of inflammatory myofibroblastic tumor. The postoperative course was uneventful, and no evidence of recurrence was observed at the six-month follow-up. Conclusion: Although rare, pediatric mesenteric IMT should be considered in the differential diagnosis of abdominal masses in children. The absence of distinctive clinical and radiologic features frequently limits accurate preoperative diagnosis, highlighting the importance of a multidisciplinary approach. Definitive diagnosis relies on histopathologic evaluation and immunohistochemical studies, including anaplastic lymphoma kinase (ALK) assessment. Complete surgical excision remains the cornerstone of management and is generally associated with favorable outcomes. This case emphasizes the need for heightened clinical suspicion and underscores the critical role of immunohistochemistry in establishing an accurate diagnosis and guiding appropriate management.