Inflammatory myofibroblastic tumor presenting as a pancreatic mass: a case report and review of the literature.

CONTEXT Inflammatory myofibroblastic tumor is a distinctive lesion of unknown etiology. It has generally been considered a rare benign pseudosarcomatous lesion of admixed inflammatory infiltrates with myofibroblastic spindle cells. Although original case descriptions focused on the pulmonary system, it is now recognized that virtually any anatomic location can be involved. However, an inflammatory myofibroblastic tumor located in the pancreas is rare. CASE REPORT We report a case of an asymptomatic 70-year-old Caucasian man with a 3.8 cm inflammatory myofibroblastic tumor located in the tail of the pancreas which was discovered incidentally on a computed tomography scan of the abdomen. Endoscopic ultrasonography with fine needle aspiration was negative for malignancy. However, because of worrisome radiographic features, a distal pancreatectomy with splenectomy was performed. The pathology revealed an inflammatory myofibroblastic tumor with focal extension into the peripancreatic soft tissues, but with negative surgical margins. The patient has been followed for 10 months without evidence of recurrence. CONCLUSIONS To date, there have been only 25 cases of inflammatory myofibroblastic tumor located in the pancreas reported in the English language scientific literature. Even with multimodal pre-surgical investigation, it can be extremely difficult to differentiate inflammatory myofibroblastic tumor from pancreatic malignancies. Most cases require surgical exploration and complete resection to obtain an accurate diagnosis. A review of published case reports is also presented.