Primary Hepatic Solitary Fibrous Tumour: A Rare Mesenchymal Entity with Distinct Histopathologic and Molecular Features

Solitary fibrous tumour is an uncommon, predominantly benign tumour of mesenchymal origin, developing mainly in the thoracic cavity and on the pleural surface, although it has been reported in a wide variety of extrapleural sites. Its occurrence in the liver is particularly rare. We present the case of a 57-year-old woman in whom a large mass was identified in the left lobe of the liver, demonstrating inhomogeneous contrast enhancement without significant compression of the abdominal vessels. The lesion measured 170 mm in its greatest diameter and severely destroyed the surrounding liver parenchyma. SFT is characterised by haphazardly arranged ovoid and spindle-shaped cells with numerous mildly staghorn-like vessels lined by flattened endothelium. It typically shows NAB2–STAT6 gene rearrangement with CD34 and/or STAT6 positivity on immunohistochemistry. Since imaging methods are not specific regarding the nature of the lesion, pathological and immunohistochemical analyses are essential for establishing an accurate diagnosis and assessing differential diagnostic possibilities.