Cholangiocarcinoma: A diagnostic dilemma on cytology.

BACKGROUND Cholangiocarcinoma is a relatively rare form of adenocarcinoma which may resemble adenocarcinoma of pancreatobiliary origin or adenocarcinomas from many other sites in the body. As a result, its diagnosis relies mainly on clinical history and morphology. CASE A 64-year-old male with cirrhosis and worsening liver failure underwent fine needle aspiration of a radiologically detected liver mass. Cytological material showed a monomorphic population of cells arranged singly and in clusters, reminiscent of a neuroendocrine tumour (NET). Cell block morphology added to the diagnostic dilemma by showing a delicate vasculature among the tumour cells. Immunohistochemistry on the cell block revealed that cells were positive for CK7 and CK19 and negative for synaptophysin and chromogranin, thereby pointing towards a pancreatobiliary origin for the tumour and excluding an NET. CONCLUSION In the case of liver aspirates, even when encountering confusing morphological entities, it is imperative to keep in mind the possibility of a rare neoplasm such as cholangiocarcinoma. In the absence of core needle biopsy, cell block sections prepared from aspirated material can provide appreciable immunohistochemistry results to resolve the diagnostic dilemma.