Natalie Cosgrove, MD, is a second year gastroenterology fellow at Thomas Jefferson University. She completed her undergraduate training at Bucknell University. She graduated with a medical degree from Temple University and completed a residency in internal medicine at the University of Virginia. She plans to pursue a career in academic advanced endoscopy.
This report describes a rare pancreatic cystic lesion called an acinar cell cystadenoma (ACA) occurring in an adolescent male who presented with abdominal pain. The cyst was initially identified on ultrasound and cross-sectional imaging. His diagnosis remained uncertain despite additional analysis including endoscopic ultrasound with fine needle aspiration. The patient underwent successful laparoscopic excision for definitive diagnosis and management with an unremarkable postoperative course. Although there are no formal recommendations for postoperative monitoring and his risk of recurrence is unknown, we recommended every other year MRI/ magnetic resonance cholangiopancreatography (MRCP) for postresection surveillance due to the theoretical risk of recurrence with malignant transformation.
Incidental pancreatic cystic lesions are becoming increasingly common with more widespread use of cross-sectional imaging. Pancreatic acinar cell cystadenocarcinoma and ACAs account for less than 5% of these lesions. ACAs are rare pancreatic cysts that have been described in several case reports. ACAs typically arise from a background of normal pancreatic parenchyma and may be focal or diffuse in distribution. ACA may be unilocular or multilocular, with larger locules harboring internal septations. Unilocular ACAs are predominantly lined by well-differentiated acinar epithelium without atypia and scattered ductal cells, while patches of ductal epithelium within a background of acinar epithelium are more typical of multilocular ACAs.
ACAs occur predominantly in females (61%-88% female), with the age of diagnosis ranging from 9 to 66 years and mean age of onset in the fourth decade. Cysts may be incidental or symptomatic. When symptomatic, the most common presentation is pain. We describe a case of this rare cystic lesion occurring in a healthy adolescent male presenting with abdominal pain.
A previously healthy 14-year-old male presented to an emergency room with 3 to 4 days of diarrhea and abdominal pain in November 2014. Abdominal X-ray demonstrated dilated loops of bowel consistent with gastroenteritis. His serum AST was slightly elevated at 65 units/L (ULN 37), however his remaining hepatic function panel, complete blood count, lipase and amylase were normal. An abdominal ultrasound suggested a cystic structure medial to the left kidney with thickened internal septations. Despite repeating the abdominal ultrasound in multiple planes, it remained unclear if the structure represented a distended fluid-filled loop of colon or a unique cystic lesion. Subsequent computerized axial tomography (Figure 1) revealed a multiseptated cystic structure in the pancreatic tail measuring 3.5 x 4 x 5 cm with peripheral hyperdensities compatible with extrapancreatic calcifications. Several of the cystic components demonstrated thickened walls with mild enhancement. The pancreatic parenchyma and pancreatic duct appeared normal. No other pancreatic lesions were identified. Multiple mildly dilated fluid-filled loops of large and small bowel with air-fluid levels compatible with gastroenteritis were also noted, which were felt to be the likely etiology of his symptoms.
Figure 1. Computer tomographic scan of abdomen. Multiseptated cystic structure in the pancreatic tail (3.5 x 4 x 5 cm).
The patient’s symptoms resolved shortly following his emergency room visit, with normalization of his stools and resolution of his abdominal pain. After careful review of his images, his pancreatic lesion was felt to represent a cystic pancreatic mass and less likely a pseudocyst or a solid pseudopapillary tumor with cystic components. He was referred for an endoscopic ultrasound (EUS) to further characterize his lesion. An EUS (Figure 2) performed December 2014 noted a 2.2 x 2.2-cm thick walled pancreatic tail lesion with a hypoechoic center and several adjacent anechoic lesions, the largest of which was 2.3 x 1.3 cm. The pancreas otherwise appeared normal. Fine needle aspiration of the largest anechoic lesion was performed using a 22g Expect needle (Boston Scientific). One milliliter of pink tinged nonviscous fluid was aspirated. Cyst fluid analysis revealed CEA 7.1 ng/mL and amylase 633 U/L. Aspirate cytology was nondiagnostic with rare small groups of mildly atypical epithelial cells, benign acinar cells, ductal cells and fragments of fibrous tissue and debris. RedPath PathFinderTG integrated diagnosis was also indeterminate, due to lack of polymerase chain reaction amplifiability from low DNA quantity and poor DNA quality.
Figure 2. Endoscopic ultrasound image of a 2.3 x 1.3 cm anechoic lesion adjacent to the pancreatic tail.