MRI diagnosis of rupture of pancreatic pseudocyst into portal vein: case report and review of literature
A 52-year-old male, chronic alcoholic and smoker presented to the emergency department with acute abdominal pain. The serum amylase level was elevated and a diagnosis of acute pancreatitis was made. The patient was managed conservatively and was satisfactorily discharged after a two week-stay in hospital. The patient developed abdominal pain again after 2 months and presented to the outpatient department at another institute where a diagnosis of acute on chronic pancreatitis was made. The patient was referred and when he presented to us he was ambulatory and complained primarily of vague upper abdominal pain with no signs of peritonitis. He also complained of occasional episodes of vomiting and weight loss. He was carrying a report of an endoscopic ultrasound (EUS) done elsewhere, films of which were not available. The EUS report showed a 3×3 cm pseudocyst in the region of neck of pancreas with possible communication with dilated main pancreatic duct (MPD). The pseudocyst was compressing the distal common bile duct (CBD) causing moderate biliary dilation. At our institution, he was further evaluated with a transabdominal USG and a contrast enhanced CT (CECT) to look for the severity and extent of disease. The USG () showed the portal vein as anechoic but with no color flow within and also showed communication between the cyst and portal vein. The CECT showed the pseudocyst () in the pancreatic neck and completely thrombosed portal vein and its branches () which was misinterpreted as dilated CBD on EUS. There were multiple periportal collaterals and areas of necrosis in segment V and VII of liver which showed subtle peripheral enhancement and were considered as cholangiolar abscesses. There was suggestion of communication of the pseudocyst with the MPD.\nMRI was performed to investigate a possible communication of the pseudocyst with the MPD and to further characterize the liver lesions. It showed the pseudocyst at the neck of the pancreas with communication with the dilated MPD. The cyst was seen just above the spleno-portal confluence with a defect in the posterior wall and a possible direct communication with the portal vein. The portal vein showed a signal characteristic consistent with fluid i.e. homogenously hyperintense on T2-weighted imaging and hypointense on T1-weighted imaging. There was some plaque-like material along the wall of the main portal vein and its branches which showed hyperintense signal on T1-weighted imaging and hypointense on T2-weighted imaging (, ). On post contrast images there was no opacification of the portal vein (). These features did not correlate with the expected signal character of the thrombus but rather confirmed the presence of fluid within the portal vein similar to that in the pseudocyst with the plaque-like material along the wall showing the character of residual lysed thrombus. There were non-enhancing areas of necrosis in segments V and VII of the liver and thrombus in the distal part of the superior mesenteric vein and splenic vein. The CBD was normal in caliber and there was no intrahepatic biliary dilation. Thus a diagnosis of rupture of pancreatic pseudocyst into the portal vein with lyses of the portal vein thrombus and associated liver necrosis was made. The MRI findings suggested this diagnosis thus obviating the need of any invasive diagnostic modality. Since the main complaint of the patient was generalized abdominal pain and distention which was well controlled with regular medication, a decision to continue with conservative treatment was taken and the patient was kept on close follow up and review. The patient did well thereafter with no significant increase or development of complaints on 6-month follow up. The patient is still on regular follow up and doing well.