IgG4-related disease - retroperitoneal fibrosis

Case contributed by Dr Eid Kakish

Presentation

Painless jaundice. Positive history of hypertension and diabetes. Unknown drug history.

Patient Data

Age: 70 years
Gender: Male

CT Scan (Pancreatic Protocol)

CT

The pancreas appears bulky, specifically the pancreatic head and uncinate process, surrounded by minimal peripancreatic fat stranding. Multiple enlarged peripancreatic lymph nodes can be appreciated in the suprapancreatic and pancreaticoduodenal stations. 

The common bile duct appears dilated, with evidence of distal common bile duct wall thickening, and associated intrahepatic biliary tree dilatation, more marked in the left lobe of the liver. 

The liver, however, is of normal size and contour, with no focal liver lesions. 

The abdominal aorta appears diffusely diseased, with multiple atherosclerotic plaques. A low attenuation, circumferential periaortic mass is seen surrounding the abdominal aorta, superior mesenteric artery, right colic artery and inferior mesenteric artery, and extends down to involve both common iliac and internal iliac arteries. This mass appears isodense to the abdominal aorta and IVC in the delayed phase, in keeping with delayed enhancement, likely relating to advanced disease. No significant anterior displacement of the abdominal aorta or the IVC is seen.

Both ureters appear to be embedded within the retroperitoneal fibrotic mass, with medial deviation and abrupt tapering at the level of L4 vertebral body. Mild bilateral hydronephrosis is evident.

No focal lytic or sclerotic lesions are seen in the imaged portions of the spine or the bony pelvis.  

Annotated image

Coronal: circumferential periaortic mass surrounding the abdominal aorta (Red Arrows)

Axial: distal common bile duct wall thickening (Red Circle)

Coronal oblique MIP: Medially deviated ureters with mild proximal dilatation (Yellow asterisks)

Case Discussion

The patient was referred for a CT scan by the gastroenterology team to rule out a pancreatic head tumor. 

Patient's serum IgG4 serum levels were performed after his initial CT, and were found to be markedly elevated.

The imaging findings of a bulky pancreatic head, with associated common bile duct and intrahepatic biliary tract dilatation can be misleading in this case. In pancreatic ductal adenocarcinomas, the tumor appears hypodense and poorly enhancing compared to the normal surrounding pancreatic tissue, appearing hypodense in the arterial phase in 75-90% cases, and may show delayed enhancement. In this particular case, the whole appearance of the pancreas is homogenous in all phases, with minor surrounding fat stranding, raising the possibility for other diagnoses. Please see: Pancreatic ductal adenocarcinoma

Looking at the imaging findings surrounding the abdominal aorta, with no aortic elevation, retroperitoneal fibrosis moves up in the list of the differential diagnoses.

A correlation between retroperitoneal fibrosis, sclerosing cholangitis, and autoimmune pancreatitis can be found in medical literature. Please see: IgG4-related disease

This patient's condition significantly improved after the initiation of steroid therapy, with complete regression of his symptoms. 

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