Cystic pancreatic lesions: From increased diagnosis rate to new dilemmas

Abstract

Cystic pancreatic lesions vary from benign to malignant entities and are increasingly detected on cross-sectional imaging. Knowledge of the imaging appearances of cystic pancreatic lesions may help radiologists in their diagnostic reporting and management. In this review, we discuss the morphologic classification of these lesions based on a diagnostic algorithm as well as the management of these lesions.

Keywords: Cyst; IPMN; MRI; Pancreas.

Figure 1

Decision algorithm for pancreatic cystic lesion diagnosis (IPMN: intraductal papillary mucinous neoplasm; MCN: mucinous cystadenoma; NET: neuroendocrine tumor; SPEN: Solid and papillary epithelial neoplasm; FNH: focal nodular hyperplasia).

Figure 2

Coronal T2 (a) and MRCP sequence (b) showing a small T2 hyperintense lobulated lesion (arrowhead) communicating (arrow) with the main pancreatic duct consistent with a side branch IPMN (intraductal papillary mucinous neoplasm).

Figure 3

Axial T2-WI (a) demonstrates two large lobulated T2 hyperintense body and tail lesion (arrows). MRCP (b) shows the largest body lesion communicating with the main pancreatic duct (arrow). The mass (arrows) does not show internal complexity or enhancement after intravenous administration of a gadolinium chelate (arrows, c). The main pancreatic duct is not dilated. These features are consistent with side branch IPMNs (intraductal papillary mucinous neoplasms).

Figure 4

Coronal T2-WI (a), MRCP sequence (b) and axial T2-WI (c) demonstrate a diffuse (arrows) dilatation of the main pancreatic duct until the major papilla without evidence of stenosis. Axial T2-WI (c) shows intermediate T2 soft-tissue mass lateral to the main pancreatic duct (arrowhead) which demonstrates enhancement after gadolinium injection (arrowhead, d). These features are consistent with degenerated main duct IPMN (intraductal papillary mucinous neoplasm).

Figure 5

Proposed management algorithm of side branch IPMN (IPMN: intraductal papillary mucinous neoplasm; MPD: main pancreatic duct; EUS: endoscopic ultrasound).

Figure 6

Axial T2-WI shows a complex cyst with a fluid-debris level (arrow) in the pancreatic tail (a). On contrast-enhanced image (b), there is enhancement of surrounding wall (arrow) but no internal enhancement in keeping with a pseudocyst.

Figure 7

Coronal (a) and axial T2-WI (b) demonstrate a well-defined large pancreatic lesion, consisting of a cluster of many small cysts (arrow, a) separated by thin septa. The central focal region of T2 signal hypointensity (arrowhead, b) from which the thin septa radiate is in keeping with a calcified scar as shown on CT (arrow, d). Axial delayed contrast-enhanced MRI (c) demonstrates thin enhancement of the internal septa (arrows). These are all features of benign serous cystadenoma.

Figure 8

Axial T2-WI shows well-circumscribed hyperintense lesion (arrow) in the tail of pancreas that does not show communication with pancreatic duct. The mass (arrows) does not show internal complexity or enhancement after intravenous administration of a gadolinium chelate (b). On contrast-enhanced image, there is subtle delayed enhancement of surrounding wall (arrow). These features suggest mucinous cystadenoma.

Figure 9

Cystic pancreatic endocrine neoplasm: axial T2-weighted image (a) T2-WI showing a well-circumscribed unilocular hyperintense lesion (arrow) in tail of pancreas. On enhanced sequence, the mass shows avid rim enhancement (arrow) in early arterial phase image (b), persistent on portovenous phase (arrow, c).

Figure 10

Axial contrast-enhanced CT image shows 6-cm hypo-vascular, well-circumscribed mass in body and tail of pancreas with internal nodularity (arrowhead) and thick enhancing wall (arrow) in keeping with a solid and papillary epithelial neoplasm.

Figure 11

Summary of the different cystic lesion of the pancreas (SCN: serous cystadenoma; MCN: mucinous cystadenoma; IPMN: intraductal papillary mucinous neoplasm; SPN: solid and papillary epithelial neoplasm; PEN: pancreatic endocrine neoplasm; CP: chronic pancreatitis; EUS: endoscopic ultrasound).