Primary hepatic malignant fibrous histiocytoma mimicking hepatocellular carcinoma: A report of two cases

Abstract

Malignant fibrous histiocytoma (MFH) is a tumor that occurs throughout the body as a relatively uncommon entity. The current study presents two cases of primary malignant fibrous histiocytoma of the liver. The first case was of a 67-year-old male who exhibited no symptoms or abnormal physical signs, and in whom the lesion was found by ultrasound examination during a routine physical examination. The second case was of a 35-year-old male who presented with persistent malaise, weight loss and intermittent right upper quadrant pain. The presence of liver cirrhosis due to hepatitis B virus, which was identified 10 years previously, and the clinical appearance caused MFH to appear as hepatocellular carcinoma at the time of the initial diagnosis. Abdominal magnetic resonance imaging scans were the main tools of diagnosis, but the MFH mimicked hepatocellular carcinoma due to the similar morphological characteristics, the rare occurrence of MFH and the underlying diseases of the liver. The first patient underwent a complete resection and recovered well, while the second patient underwent palliative treatment due to the large size of the tumor and the obstructive emboli in the portal vein. The diagnoses of the tumors were confirmed as MFH by histopathology and immunohistochemistry.

Keywords: histology; magnetic resonance imaging; malignant fibrous histiocytoma.

Figure 1

Case one: A 67-year-old male with primary malignant fibrous histiocytoma of the liver. (A) Magnetic resonance (MR) T1WI revealing a round-shaped mass, with hypointense areas in the tumor. (B) MR T2WI revealing a non-heterogeneous, hypointense lesion in the liver, with several discrete hyperintense areas in the central section of the tumor. (C) Contrast-enhanced T1WI revealing a large multilocular cystic mass, with a cystic wall, fibrous septa and enhancement of solid components. (D) Photomicrography of the round mass, consisting of closely packed spindle cells forming a storiform pattern (hematoxylin and eosin; ×100 magnification). (E–G) Tumor cells exhibiting immunoreactivity for vimentin (×100 magnification), cluster of differentiation 68 (×100 magnification) and cytokeratin 8 (×100 magnification), respectively. WI, weighted imaging.

Figure 2

Case two: A 35-year-old male with liver cirrhosis due to hepatitis B virus infection and a tumor of the right lobe, confirmed to be a primary malignant fibrous histiocytoma of the liver. (A) The lesion is inhomogeneous on unenhanced T1WI and is mainly hypointense, with an irregular high intensity area in the left section of the mass. (B) The lesion possesses a well-defined margin and is inhomogeneously hyperintense on T2-weighted spin-echo magnetic resonance imaging, with numerous round- or oval-shaped patchy hyperintensity areas in the lesion. The intrahepatic biliary ducts are dilated. (C) Following IV administration of gadopenate dimeglumine, the heterogeneous enhancement of the tumor, with central hypointense sections, is clearly visible. (D) Hematoxylin and eosin staining of the pathological specimen (×100 magnification) reveals the spindle to consist of oval tumor cells arranged in a criss-cross fashion. (E–G) Immunohistological staining for vimentin (×100 magnification), cluster of differentiation 68 (×100 magnification) and for cytokeratin 8 (×100 magnification), respectively, demonstrating a positive reaction in the tumor cells. WI, weighted imaging.