When a Cough Hides a Rare Diagnosis: An Inflammatory Myofibroblastic Tumor in a Pediatric Patient—A Case Report ^†

Introduction: An inflammatory myofibroblastic tumor (IMT) is a type of tumor that is considered rare in the literature; it has a highly nonspecific and variable clinical profile, often being confused with other pathologies. In this report, we will describe the clinical, radiological, histopathological, and immunohistochemical aspects of a typical pediatric IMT, highlighting the diagnostic challenges and the importance of an interdisciplinary approach in the evaluation of mediastinal masses in pediatrics. Methodology: This study was based on a descriptive case report of an 11-year-old child. A systematic search was also carried out across databases (such as PubMed, Scielo, and BVS) for studies published between the years 2020 and 2024, using specific keywords and inclusion criteria for articles on IMT. Results: The clinical case describes an 11-year-old male patient who presented with a persistent dry cough and difficulty gaining weight for three months, initially treated as pneumonias without improvement. Imaging revealed a mediastinal mass, and biopsy, followed by histopathological and immunohistochemical analysis, confirmed the diagnosis of an IMT. The findings demonstrated the proliferation of morphologically benign spindle cells and a lymphoplasmacytic inflammatory infiltrate, with positive markers for its myofibroblastic nature, ruling out the possibility of aggressive malignancy. Conclusions: The analysis of this case reinforces the need to consider IMT in the differential diagnosis in cases of nonspecific symptoms with pulmonary involvement. Accurate diagnosis and complete surgical resection are the gold-standard approach. The absence of molecular analysis for ALK gene rearrangements was a limitation of this case, underlining the importance of future investigations and multidisciplinary and systematic approaches for these rare conditions.