Hepatic solitary fibrous tumour

A 39-year-old woman was referred to our institution with a history of inappetence and abdominal bulging on the right flank. She had no relevant medical history or any prior medical complaints. 

Magnetic resonance (MR) imaging of the superior abdomen demonstrated a large, well-defined mass involving the left hepatic lobe and the anterior segments of the right lobe, with a compressive effect on adjacent organs, measuring approximately 20,4 x 18,0 x 12,0 centimetres (2291 cc). The lesion exhibited low signal intensity on T1-weighted images and heterogeneous signal on T2-weighted images, with many thick and confluent septa and multiple areas of T2-hypointensity, which suggested a fibrous component. Diffusion-weighted images showed many areas of restricted diffusion. Post-contrast images showed vivid enhancement in the arterial phase via hepatic artery branches and also from smaller branches of the left gastric artery, with progressive heterogeneous enhancement in the delayed phases. There were no areas of washout, fat or necrosis within the lesion. 

Surgical resection of the lesion was not feasible owing to the absence of a clear demarcation between the lesion and adjacent hepatic veins, so the patient underwent surgical biopsy. Histologic and immunohistochemical analysis confirmed the diagnosis of a paucicellular solitary fibrous tumour (SFT) of the liver.

SFTs are rare neoplasms of mesenchymal origin, most commonly benign, but with some reported cases of malignancy, including metastatic spread [1,2]. They are extremely rare in sites other than the pleura, with fewer than a hundred cases of hepatic SFT reported in current literature [3,4]. Patients are most commonly middle-aged adults, and there is a slight female predominance [2].

Clinical symptoms are usually nonspecific and may include weight loss, fatigue, abdominal fullness and discomfort [2]. Up to 80% of patients can be asymptomatic at the moment of diagnosis [4]. Since these tumours can be very large, they may also cause symptoms secondary to compression of adjacent viscera and abdominal structures [2].

Although imaging findings are also nonspecific, some features can point the radiologist towards the direction of this diagnosis [2,4]. Sonography may show a heterogeneous mass, which can contain cystic areas or calcifications [2]. Computed tomography (CT) images typically show a large, heterogeneous and hypervascular tumour, with progressive and heterogeneous enhancement, which typically displaces and compresses neighbouring organs and vessels [4]. MR imaging findings are similar to CT findings but may provide additional information in that the areas of low signal intensity on T2-weighted images suggest a fibrotic component, which is a key feature of this type of lesion [4]. The combination of these features on a noncirrhotic liver should evoke the possibility of an hepatic SFT [4]. The final diagnosis, however, is typically based on histopathological and immunohistochemical features [5,6]. 

Surgical resection is usually the modality of choice for treatment and is curative in most cases [5]. Since hepatic SFT is an extremely rare entity, long-term prognosis and alternative treatment options are yet to be defined, and continued follow-up is advised [2,5].

When facing a large, well-defined, solitary hepatic mass with features suggestive of a fibrous component, radiologists must always consider a SFT in the differential diagnosis and alert the referring physicians and pathologists of this possibility to improve diagnostic accuracy and patient outcome [4].