Radiopathologic findings of multifocal nodular hepatic steatosis

Abstract

Multifocal nodular hepatic steatosis (MFNHS) is a rare benign clinical entity mimicking metastatic disease. This study is designed to describe the imaging and histopathologic findings and clinical course of patients with MFNHS. In this retrospective study during 2005 and 2023, 10 patients with an imaging and pathologic diagnosis of MFNHS were included. The imaging and histopathology findings were reviewed in each case. The follow-up images were reviewed to assess the clinical course of the disease. The mean age was 50.0 ± 10.5 years, and the male-to-female ratio was 4:6. Three patients had a past medical history of cancer. All patients were found to have lesions suspicious of malignancy on either ultrasound (US) or computed tomography (CT) requiring further workup. Six patients underwent magnetic resonance imaging (MRI), and 4 patients underwent an image-guided biopsy which resulted in hepatic steatosis. During the follow-up period, the majority of patients (71.5%) remained unchanged or improved, while 2 patients (28.5%) progressed. MRI is a reliable modality in detecting and characterizing MFNHS and should be considered to further assess multiple hepatic lesions in cases where the clinical suspicion is not high for metastasis.

Keywords: Magnetic resonance imaging; Metastasis; Multifocal nodular hepatic steatosis.

Fig. 1

(A) Transverse US image showing multiple hyperechoic round well-defined lesions (solid arrow) with posterior acoustic enhancement (dotted arrows). (B) Coronal CT image in the arterial phase, and the portal venous phase (C) showing multiple non-enhancing round hypodensities throughout the hepatic parenchyma.

Fig. 2

Unenhanced T1 (A) and T2 (B) weighted images showing multiple round lesions throughout the liver demonstrating low signal intensity on T1 and iso to mildly high signal intensity on T2-weighted images. The lesions show signal dropout on the out-phase image (D) compared to the in-phase image (C) and do not enhance or restrict diffusion on contrast-enhanced (E) and diffusion-weighted images (F).

Fig. 3

Anterior (A) and posterior (B) views of the nuclear medicine Liver-Spleen scan showing geographic areas of decreased colloid uptake. Scout PET image showing no hypermetabolic lesion within the liver.

Fig. 4

Histopathology exam in patient 1. (A) H&E at 10x magnification demonstrates benign hepatic tissue with small areas of focal, mild, steatosis (yellow circle). There is stage II periportal fibrosis and mild inflammation of the portal tracts (arrow). (B) A trichrome special stain of the same biopsy at 10x magnification highlights the periportal fibrosis without any additional pathologic findings. There are no vascular lesions identified in the submitted tissues. (C) 20x magnification of the biopsy demonstrating both the focal macrovesicular steatosis (black arrow) and some clinically insignificant microsteatosis (yellow arrow).