Three cases of mediastinal pancreatic pseudocysts

Abstract

A rare complication of acute or chronic pancreatitis is the formation of a mediastinal pancreatic pseudocyst (MPP), which is caused by tracking of pancreatic fluids through anatomical openings of the diaphragm into the mediastinum. Herein, we report the imaging characteristics of three cases of this condition. Our results revealed three features in common: (i) the connection between the mediastinum and the pancreatic cystic lesion; (ii) the presence of pleural effusions; and (iii) imaging findings consistent with chronic pancreatitis, such as pancreatic atrophy and calcifications and dilatation and/or stricture of main pancreatic duct (MPD). Serial diameter changes of the MPD and of the adjacent pseudocysts were necessary for the determination of the therapeutic strategy used in each case.

Keywords: Pancreatic pseudocyst; computed tomography (CT); management strategy; mediastinal extension; thoracopancreatic fistula.

Fig. 1.

Pancreatic pseudocysts in Case 1. (A) Axial enhanced chest CT at symptom onset. Cystic lesions (arrows) extending from the abdomen into the mediastinum along the esophagus and aorta. Bilateral pleural effusions are seen. The esophagus (arrowhead in white) is located behind the cystic lesion (short arrow). (B) Coronal enhanced lower chest and upper abdominal CT at symptom onset. The connection between the mediastinal and abdominal cystic lesions (short arrows) is well identified on the coronal image. One of the cysts (arrowhead in black) is connected to the pancreas body (arrowhead in white). (C) Axial enhanced upper abdominal CT at symptom onset. The pancreatic cyst with the black arrowhead is the same as the cyst with the black arrowhead noted above (B). A calcification is seen in the pancreas body. The main pancreatic duct (MPD) of the pancreas tail is slightly dilated (arrow). The cystic lesion (long arrow) extends into the retrocrural space. (D) Axial enhanced upper abdominal CT obtained 8 months after symptom onset. The size of the pancreatic cyst is enlarged (arrowhead in black).

Fig. 2.

Pancreatic pseudocysts in Case 2. (A) Sagittal enhanced chest and upper abdominal CT. Cystic lesions (arrows) extending into the mediastinum along the esophagus (arrowheads in white). The connection between the mediastinal and abdominal cystic lesions (arrows) is well identified on the sagittal image. (B) Axial upper abdominal fat-suppressed T2-weighted image at symptom onset. Cystic lesions (arrows) are seen in the peripancreatic region. A small cyst is seen in the pancreas body (arrowhead in black). The adjacent MPD is slightly dilated (arrowhead in white). (C) Axial unenhanced upper abdominal CT obtained one month after symptom onset. A tube stent (arrowhead in white) is placed in the MPD. A pigtail drainage catheter (arrow) is placed in the dorsal cyst of the pancreas body. (D) Axial enhanced upper abdominal CT obtained 1 year after symptom onset. Both the cyst (arrowhead in black) and the adjacent MPD (arrowhead in white) are enlarged again. The dorsal cyst of the pancreas body has disappeared (arrow).

Fig. 3.

Pancreatic pseudocysts in Case 3. (A) Axial enhanced chest CT at symptom onset. Mediastinal fluid collections with cystic lesions (arrows) extend along the esophagus (arrowheads in white) and inferior vena cava (arrowhead in black). Bilateral pleural effusions and pericardial effusions are seen. (B) Sagittal enhanced lower chest and upper abdominal CT at symptom onset. The connection between the cysts (arrows) around the liver (asterisk) and the esophagus (arrowheads in white) and the pancreas head with multiple cysts (short arrows) is well identified on the sagittal image. (C) Axial enhanced upper abdominal CT at symptom onset. The pancreas head with multiple cysts (short arrow) and calcification (long arrow) is seen. MPD dilatation (arrowhead in white) is seen in the pancreas body and tail. MPD stricture (arrowhead in black) is suspected in the pancreas head. (D) ERCP obtained 1 week after symptom onset. Dilatation and irregularity of the side branches (short arrows in white) and an MPD stricture (arrowhead in black) are seen in the pancreatic head region.