ABSTRACT: Presentation of the Case A 37-year-old woman presented at 35 weeks of gestation with her third child with failure to adequately gain weight and was noted by her obstetrician to have delay in the growth of her baby. Ultrasound of the abdomen incidentally revealed the presence of a liver lesion. After additional evaluation, she ultimately delivered her daughter at 36 weeks uneventfully. She subsequently underwent additional evaluation. Liver magnetic resonance imaging (MRI) revealed a 5-cm solitary solid mass in segment 4A of the liver, concerning for malignancy. Serum ?-fetoprotein, carcinoembryonic antigen, cancer antigen (CA)19-9, CA15-3, and CA125 were all normal. Liver biopsy was positive for adenocarcinoma. The tumor cells demonstrated a phenotype suggesting a possible breast primary, although the immunohistochemistry did not support that diagnosis and the tumor was negative for mammaglobin, gross cystic disease fluid protein (GCDFP)-15, estrogen receptor (ER), and progesterone receptor (PR) (Table 1). The tumor was also CDX2 and cardiotrophin-1 negative, but cytokeratin (CK) 19 positive. Her endoscopic retrograde cholangiopancreatography, upper endoscopy, colonoscopy, breast mammogram, and breast MRI were completely normal. A positron emission tomography-computed tomography scan showed a fluorodeoxyglucose-avid 5.8-cm × 6.0-cm hypoattenuating lesion with peripheral enhancement involving segment 4 and segment 8 at the dome. In addition, central necrosis within the lesion was noted. The left main portal vein was mildly attenuated by the mass. She eventually underwent a left hepatectomy en bloc with caudate resection, portal lymphadenectomy, cholecystectomy, and omental pedicle flap. On exploration of the abdomen, no additional disease was noted. The final pathology revealed a 9.4-cm moderately to poorly differentiated adenocarcinoma of the intrahepatic bile ducts. Venous invasion was present. Perineural invasion was absent. The margins were negative. Thirteen lymph nodes were obtained, all of which were negative, consistent with a stage T2, N0, MX intrahepatic cholangiocarcinoma. The tumor was positive for CK7, CK19, and CA19-9 and negative for CK20, CDX2, CA125, ER, PR, GCDFP-15, synaptophysin, and chromogranin (Table 1). The uninvolved liver was unremarkable and a trichrome stain showed no fibrosis. Following an uneventful postoperative recovery, she was referred for consideration of adjuvant therapy.