Abdominal Inflammatory Myofibroblastic Tumour Presenting as a Pancreatic Mass: A Case Report

An abdominal inflammatory myofibroblastic tumor (AIMT), is a rare benign tumor composed of inflammatory and other mesenchymal cells. It can affect the entire body, predominantly in children and young adults. The diagnosis is challenging considering the wide clinical presentation and can often be mistaken for malignant tumors. We report a rare case of a 46-year-old female patient, who presented with intermittent abdominal pain weight loss, and an abdominal palpable mass. Abdominal ultrasound found a well-defined 18 cm, rounded mass, with solid and cystic components. Abdominal CT demonstrated a well-defined, hypodense, retro gastric mass of 20 cm, with thickened wall and heterogenous enhancement. The mass had contact with the pancreatic tail, transverse colon, spleen, left kidney pedicles, abdominal aorta, superior mesenteric vein, and mesaraic trunk with no invasion signs. The mass was initially thought to be pancreatic cancer, but given the large size, other diagnoses like sarcoma, lymphoma, or abdominal hydatid cyst were suggested. Endoscopic ultrasound found a rounded retro gastric mass of 18/12 cm, with a thickened wall and well-limited calcifications. The content was both cystic and solid with mobile vegetations, with no visible Doppler flow. The mass had contact with the body and tail of the pancreas, spleen hilum, the upper pole of the spleen, and the hepatic pedicle behind, with no invasion sign. After a multidisciplinary team meeting, a decision was taken to perform surgical resection with mass resection, distal splenopancreatectomy, and transverse and sigmoid colectomy. Pathological and immunostaining results were consistent with inflammatory pseudotumor. The postoperative recovery was uncomplicated. The patient remains asymptomatic with no obvious signs of metastasis or recurrence. AIMT represents a reel diagnostic challenge. Clinical symptoms are unspecific. Radiological and endoscopic features can often be mistaken for malignant tumors. Surgical management remains to be the best therapeutic option. We report a rare case of AIMT treated by surgery with complete resection. We suggested a long-term follow-up given the local recurrence risk.