Intrapancreatic accessory spleen: Findings on MR imaging and CT

Abstract

BackgroundAlthough intrapancreatic accessory spleen (IPAS) are infrequently noticed radiologically, they have been reported up to 2, 8% in Autopsies. The aims of this study were to describe the imaging characteristics of IPAS using computed tomography (CT) and/or magnetic resonance imaging (MRI) to prevent an unnecessary surgery. Materials and methodsDuring last 7 years, 5 consecutive patients with incidental intrapancreatic accessory spleen (IPAS) on the tail of pancreas which radiologically mimicked a neuroendocrine pancreatic tumor, surgically treated in our university hospital. Preoperative CT studies (4 of 5 patients) and MRI (2 of 5 patients, one patient had both CT and MR images), operation reports and pathological diagnoses were analyzed retrospectively. For each lesion, images were analyzed based on the characteristic signal intensities on MRI or density of the lesion on CT images and presence of contrast enhancement. Pathologic correlation was available for the lesions. ResultsThe female-to-male ratio was 2:3, with a mean age of 56 years (age range, 42–72 years). Incidental lesion findings were due to imaging studies using magnetic resonance imaging and/or computed tomography. In all the patients there was just one lesion on the tail of pancreas. On all the MR images (2 of 5 patients), a focal pancreatic lesion that was in compared to the rest of pancreas hypointense on T1-weighted sequences were detected, these lesions were hyperintesne on T2-weighted sequences; and enhanced more than the pancreas tissue in contrast enhanced series; however, the lesions were with the same intensity in compared to spleen in all the sequences. The enhancement pattern of the lesion was evaluated as serpiginous on early postgadolinium sequences. On all CT studies (4 of all 5 patients), there were no detectable lesions on pre-contrast series; however, on all arterial and venous series lesions were hyperdens in contrast to the rest of pancreas. The lesions had the same density of spleen in all series. In both MRI and CT images there were No adenopathy in the abdomen. Tumor size was among min. 9 × 12 mm to max. 16 × 18 mm. Pathological findings were intrapancreatic accessory spleen (IPAS) in all the cases. One patient had a pathological finding of Leiomyoma of the stomach too. ConclusionRadiologists and Surgeons should be aware that an incidental finding of a subtle well-marginated, rounded solitary lesion on the tail of pancreas on the CT or MR images which matches the density/or intensity of the spleen on all phases/ or sequences could be an intrapancreatic accessory spleen (IPAS); Therefore, an IPAS has to be excluded in asymptomatic patients with a lesions in the pancreatic tail before unnecessary surgery.