The combined efforts of radiology and histology: a case series of combined hepatocellular-cholangiocarcinoma

Abstract

Background: Combined hepatocellular-cholangiocarcinoma (cHCC-CCA) is a rare tumour that accounts for approximately 0.4-14.2% of all primary liver carcinomas (PLC).1 The true incidence may be under-reported, as they can be radiologically indistinguishable from hepatocellular carcinoma (HCC) or intrahepatic cholangiocarcinoma (iCCA) and may not proceed to biopsy.2 Current treatment paradigms do not necessitate pre-treatment biopsy. These tumours are distinct from collision tumours, in that they demonstrate unequivocal hepatocytic and cholangiocytic differentiation within the same tumour. This is illustrated morphologically and immunohistochemically. The diagnosis of cHCC-CCA is important, as the prognosis appears less favourable than HCC or iCCA in a number of studies. 2 Cases: We discuss three cases of cHCC-CCA diagnosed on excisional specimens at Royal Prince Alfred Hospital from 2020 to 2023. The tumours were identified incidentally at cut-up (Case 1), misclassified on preoperative imaging as HCC (Case 2), and unclassified on preoperative imaging (Case 3). Conclusion(s): cHCC-CCA is a rare PLC with a relatively poor prognosis compared to HCC but is largely indistinguishable on pre-treatment imaging. Recent studies have supported the need for histological diagnosis of liver tumours prior to treatment, especially in the era of targeted therapies.3 Our case series highlights the important role of histological assessment in accurate diagnosis.