Bile duct adenocarcinoma is an uncommon malignancy of the hepatobiliary system. In this case, the diagnosis was made based on cytologic sampling by endoscopic retrograde cholangiopancreatography (ERCP). Several key cytological features of adenocarcinoma are present in the current specimen and include three dimensional (3-D) cell clusters with nuclear molding and anisonucleosis. Nuclear features such as irregular nuclear contours, enlargement, chromatin clumping, and increased nuclear-cytoplasmic ratios are also seen (defined as a nuclear to cytoplasmic ratio greater than 2:1 or in which the nucleus constituted more than 50% of the entire cell volume). (Cohen MB et al., 1995; Avadhani V et al., 2017). Reactive epithelium is seen at the top right of the slide.

A wide variety of conditions both benign and malignant can lead to bile duct strictures and jaundice, and their differential diagnosis is difficult when based only on clinical and radiological findings. If clinical suspicion warrants pathologic evidence of biliary disease, one can obtain cytological specimens from ERCP, and subsequently stain them with Papanicolaou (Pap) solution to assess cytological features of malignancy. Assessment may be difficult with bile duct brushings due to poor specimen quality and quantity. In addition, inflammation, and atypia that may be seen with stenting makes the differentiation between benign or reactive biliary epithelium from neoplastic epithelium especially challenging (Avadhani V et al., 2017).

See related content for references:

1) Cohen, MB., et al. Mod Pathol. 1995 Jun;8(5):498-502.
2) Avadhani, V., et al. Mod Pathol. 2017 Sep;30(9):1273-1286.