Solid-Tubulocystic carcinoma: A new variant of intrahepatic cholangiocarcinoma

Abstract

A new variant of intrahepatic cholangiocarcinoma (iCCA) has been recognized in recent years presenting predominantly as a large hepatic mass in young woman with the characteristic expression of inhibin by immunohistochemistry. This variant iCCA was originally termed as cholangioblastic variant of iCCA, and subsequently proposed to be renamed as inhibin-positive hepatic carcinoma or solid-tubulocystic variant of iCCA to better reflect its immunohistochemical profile or morphologic spectrum. The tumor histologically is composed of small to medium sized cells with scant to moderate amount of eosinophilic cytoplasm heterogeneously organized in solid, tubular, and cystic growth patterns. The tumor cells are positive for biliary markers, inhibin and albumin, and have a novel recurrent gene fusion, NIPBL::NACC1. Awareness of this new iCCA variant and its clinicopathologic features will aid in the diagnostic work-up and avoid confusion with other primary and metastatic hepatic neoplasms.

Keywords: Cholangioblastic; Cholangiocarcinoma; Inhibin; Intrahepatic; Solid-tubulocystic.

Figure 1

Solid-tubulocystic variant of intrahepatic cholangiocarcinoma. A: Representative picture of a resected solid-tubulocystic variant of intrahepatic cholangiocarcinoma (right) in a non-cirrhotic liver (left). The tumor is well demarcated from the background liver (20x, Hematoxylin-eosin stain); B: Representative picture showing the tumor with solid, tubular, and cystic growth patterns (200x, Hematoxylin-eosin stain); C: Representative picture showing the tumor cells are positive for inhibin (200x, immunohistochemical stain); D: Representative picture showing tumor cells are positive for albumin (200x, in situ hybridization).