Malignant Transformation of an HNF1a-Inactivated Hepatocellular Adenoma to Hepatocellular Carcinoma

Abstract

Hepatocellular adenomas (HCA) are rare benign tumors of the liver, occurring predominantly in females using oral contraceptives. Our case describes a 66-year-old woman presenting with a palpable mass in her upper abdomen. Contrast-enhanced computed tomography and magnetic resonance imaging showed a large exophytic mass protruding from the caudal border of liver segments IV and V, without visible metastases. Laparoscopic resection of the tumor and gallbladder was performed. Histopathological examination showed a hepatocellular carcinoma with areas of HNF1a-HCA (H-HCA). This case shows that malignant transformation is possible in H-HCA. We present our preoperative decision-making process, as well as the role of imaging techniques in this rare case.

Keywords: Hepatocellular adenoma; Hepatocellular carcinoma; Hepatocyte nuclear factor 1-alpha; Imaging; Laparoscopy; Surgical resection.

Fig. 1

CT and MRI of the exophytic liver tumor. a Coronal contrast-enhanced CT image of the abdomen at the portal venous phase showing the large exophytic mass originating from the caudal border of liver segments 4B and 5 with a heterogeneous enhancement pattern. b Axial fat-suppressed T2-weighted MR image showing the large tumor with heterogeneous hyperintense signal intensity. c–e Axial fat-suppressed T1-weighted MR images at the arterial (c), portal venous (d), and delayed phase (e), showing slight heterogeneous, predominantly peripheral arterial enhancement, with increasing enhancement at the portal venous and delayed phases. No significant drop of signal intensity was present at the opposed-phase T1-weighted images (not shown).

Fig. 2

Macroscopic aspect. Fresh resection specimen whole (a) and sliced (b). Almost the whole specimen was lesional and consisted of a multinodular tumor with partial myxoid/necrotic aspect and partial capsule formation. The different nodules were microscopically not clearly demarcated in HCC or adenoma, with an intimate mixture of the two components. Microscopic aspect. c Both components present, with the HCC component on top of the image and the adenomatous component at the bottom. The HCC is characterized by trabecular and pseudoglandular structures, while the adenomatous component consists of atrophic hepatocytes with some sinusoidal dilatation while unpaired arteries are present and portal tracts are absent (HE. ×10). d The same area in the reticulin stain. Note the disrupted reticulin framework and the thickened pseudoglandular structures in the HCC component, while the reticulin framework is preserved in the adenoma component.

Fig. 3

Microscopic aspect with staining. Images were acquired through digital pathology. Objective is shown. a CD34 control staining at ×5. b CD34 staining at ×5. c LFABP control staining at ×5. d LFABP staining of the HCC at ×10. e LFABP staining of the border between lesional and non-lesional tissue at ×1. f Amyloid-AA staining with control at ×1. g CRP staining at ×5. h CRP control staining at ×10. i Beta-catenin control staining at ×10. j Beta-catenin staining at ×10. k Glutamine staining at ×5. l Glutamine control staining at ×5.