Solitary fibrous tumor in the liver: case report and literature review

Abstract

Background: Solitary fibrous tumors (SFTs) are uncommon mesenchymal neoplasms that present most commonly at intrathoracic sites. SFTs of the liver are rare, with only a few having been reported in the English-language literature. We report a rare case of a hepatic SFT and literature review.

Case presentation: A 49-year-old woman underwent surgery for a cranial hemangiopericytoma two decades previously. She currently presented with malaise. Abdominal computed tomography (CT) showed a huge, sharply demarcated mass in the anterior segment of the liver. Tumor marker levels were within the normal range. Following central bisegmentectomy of the liver, histological examination of the specimen revealed that the tumor was composed of spindle and fibroblast-like cells with collagenous stroma. Immunohistochemically, the spindle cells were negative for CD34 but positive for STAT6. The NAB2-STAT6 fusion gene was detected by the reverse transcription polymerase chain reaction. A diagnosis of SFT was thus confirmed histopathologically and genetically.

Conclusions: The SFT of the liver is an uncommon finding. Because there are no specific imaging features, it is difficult to diagnose the hepatic SFT preoperatively. We consider that careful surgical resection and postoperative follow-up are necessary for hepatic SFTs.

Keywords: Malignant; Radiology and pathology; Solitary fibrous tumor.

Fig. 1

Contrast-enhanced abdominal computed tomography (CT). Plain CT shows a well-defined low-density mass occupying the right lobe (14.0 cm diameter) (a). Contrast-enhanced CT shows heterogeneous enhancement in the peripheral mass during the arterial phase (b). Enhancement is then centripetal and more pronounced during the portal phase (c) and finally progresses to persistent, less heterogeneous enhancement during the delayed phase (d)

Fig. 2

Magnetic resonance imaging (MRI) and [¹⁸F]-fluorodeoxyglucose positron emission tomography (FDG-PET). Abdominal MRI shows low intensity on a T1-weighted image (a) and heterogeneously high or iso intensity on a T2-weighted image (b). Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced MRI reveals a hypointense mass during the hepatobiliary phase (c). Diffusion-weighted imaging shows higher intensity than for normal liver parenchyma (d) with a high b value of 1000 (e). FDG-PET shows no accumulation of [¹⁸F]-FDG (f)

Fig. 3

Macroscopic and microscopic findings of SFT. Macroscopically, the tumor mass was firm and yellowish-white with an intact capsule (13.3 cm maximum diameter) (a). Microscopically, the tumorous tissue showed a proliferation of oval to short spindle-shaped cells arranged in a “pattern-less pattern” (H&E × 400) (b). Immunohistochemically, the tumor cells were negative for CD34 (× 400; c), but positive for STAT6 (nuclei, × 400) (d) and vimentin (× 400) (e). Ki67 labeling index was < 5% (× 400) (f)

Fig. 4

NAB2–STAT6 fusion gene in the SFT identified by RT-PCR and sequencing. Gel electrophoresis of PCR products reveals the various NAB2–STAT6 fusion genes with heterogeneous exon compositions in the tumor, which were identified using seven primer pairs (a). Direct sequencing shows the junction breakpoint in a stretch of NAB2 intronic sequence between the 3′-end of the NAB2 exon 6 and the 5′-end of the STAT6 exon 16 (b)