Radiologic findings of an adolescent epithelioid inflammatory myofibroblastic sarcoma

Epithelioid inflammatory myofibroblastic sarcoma, a variant of the inflammatory myofibroblastic tumor, is a rare tumor that is not well described in the radiologic literature. We present a case of a 14-year-old male adolescent who presented with fever, fatigue, and weight loss symptoms and was found to have an abdominal mass on contrast enhanced CT. Initial differentials included lymphoma, pheochromocytoma, desmoid, and sarcoma, and pathological evaluation revealed an epithelioid inflammatory myofibroblastic sarcoma. The mass was separate from the surrounding structures of the left upper abdomen with unique radiologic features not previously described in the literature. Prior literature examples of epithelioid inflammatory myofibroblastic sarcoma described a heterogenous, enhancing lobulated mass, and our case was a lobulated, avidly enhancing homogenous mass on CT with surrounding inflammation and avid uptake on PET/CT. In addition to the imaging features, we describe the surgical findings, the pathologic features of the tumor, and the oncologic treatment of this patient. This case highlights the importance of including rare tumors such as epithelioid inflammatory myofibroblastic sarcoma as a potential differential consideration of an avidly enhancing homogenous abdominal mass in an adolescent.