Differential diagnosis, investigations and treatment
On physical examination, the skin was icteric, and the abdomen was soft,
flat, and without any tenderness.
Blood tests revealed elevated hepatobiliary enzymes (total bilirubin,
6.0 mg/dL; aspartate transaminase, 449 IU/L; alanine transaminase, 624
IU/L; alkaline phosphatase, 1560 IU/L; gamma-glutamyl transferase, 1163
IU/L); inflammatory markers were within normal range (white blood cell,
4600 /μL; C-reactive protein, 0.9 mg/dL); tumor markers were negative
(carcinoembryonic antigen, 2.0 ng/mL, carbohydrate antigen 19-9, 2.6
U/mL); and there was no elevation of immunoglobulin G4 (12.1 mg/dL).
Magnetic resonance imaging (MRI) performed on the 3rd day of admission
revealed a mass-like lesion around the head of the pancreas that was
hyperintense on diffusion-weighted imaging (Fig. 2).
On the 5th day of admission, endoscopic retrograde
cholangiopancreatography (ERCP) was performed. Cholangiography revealed
severe stenosis in an area of the middle to distal bile duct (Fig. 3).
Endoscopic sphincterotomy was performed, and intraductal ultrasonography
revealed homogeneous circumferential thickening (iso-hyperechoic) of the
bile duct wall at the site of stenosis (Fig. 4). Brushing cytology and
tissue biopsy of the stenotic area were performed, and a plastic stent
(straight type, 7 Fr × 90 mm) was placed for drainage. Histopathological
findings of the biopsy specimen were suggestive of adenocarcinoma, and
immunostaining of the same specimen revealed CK7, GATA3, HER2, and
mammaglobin positivity, with CDK2, CK20, PAX8, TTF1, and CA125
negativity, leading to the diagnosis of bile duct metastasis of breast
cancer (Fig. 5).