Case Presentation: The patient is a 20-year-old male with no past medical history who presented with a 6 day history of 6/10 constant sharp abdominal pain focused in the right upper quadrant (RUQ). The pain was worsened by eating, and associated with one episode of yellow, non-bloody vomiting. The patient denied any diarrhea, bloody stool, constipation, change in stool caliber, new foods, relief with bowel movements, fever, chills, dysuria, hematuria, sick contacts, rash, illicit drug use, alcohol abuse or travel outside the US. As an outpatient, he was prescribed doxycycline with no improvement. He recently had unprotected sex with a new partner. He has no known allergies, and no family history of GI disease or cancer. On admission, the patient was afebrile and hemodynamically stable. Physical examination notable for tenderness to palpation of the RUQ of the abdomen with a positive Murphy’s sign. Labs revealed an elevated white count of 11.4 K/uL with an elevated eosinophil percentage of 12.3% and an elevated eosinophil count of 1.4 K/uL. AST was 234 U/L, ALT was 452 U/L, alkaline phosphatase was 254 U/L and total bilirubin was 1.4 mg/dL. Amylase, Lipase, HIV, hepatitis, stool ova and parasite, blood cultures, CA19-9, AFP, CEA, IgG 1-4, ANCA, smooth muscle, mitochondrial and celiac disease antibodies were all normal. Ultrasound revealed diffuse gallbladder wall thickening without evidence of cholelithiasis. After an abnormal HIDA scan, an MRI of the abdomen with contrast again revealed gallbladder wall thickening now with stricture of the common bile duct with no evidence of choledocholithiasis. ERCP with biliary sphincterotomy and stent placement was performed which revealed a polypoid mass lesion extending from the mid-distal common hepatic duct to the proximal common bile duct. The gastroenterologist recommended hepatobiliary surgical consultation fearing possible cholangiocarcinoma and biopsies of the lesion were taken. However, biopsy ultimately revealed no evidence of malignancy, and instead showed biliary mucosa with intramucosal eosinophilia. The diagnosis of eosinophilic cholangitis (EC) was made, and the patient was started on a 9 week long prednisone taper, with gradual improvement of his symptoms, normalization of liver function tests, and resolution of the biliary mass on follow up ERCP three months later.

Discussion: RUQ abdominal pain can have many causes ranging from infectious to oncologic masses. In this report, we describe EC which is an extremely rare cause of biliary obstruction and on imaging can often be confounding and imitate malignancy such as cholangiocarcinoma. Peripheral eosinophilia can be associated with EC, but is not present in all cases. EC is diagnosed via tissue biopsy from the biliary tract that demonstrates histological eosinophilic infiltration. Treatment of EC is simple and utilizes oral steroids, usually with complete resolution of the mass. Prompt treatment is critical as untreated patients can suffer from hepatotoxicity and fibrosis. It is thought that an allergic mechanism plays a role in EC, as patients with EC have been noted to have increased levels of eosinophil cationic protein, IL-5 and IgE.

Conclusions: Eosinophilic cholangitis is a rare cause of abdominal pain, and can masquerade as a possible malignancy such as cholangiocarcinoma. However, treatment of eosinophilic cholangitis is straight forward, requiring oral steroids and should be considered in patients with marked peripheral eosinophilia and evidence of bile duct abnormalities on imaging.