Giant Intrapulmonary Solitary Fibrous Tumour With a Possible Liver Metastasis: A Rare Case

Intrapulmonary solitary fibrous tumours (SFTs) are exceptionally rare mesenchymal neoplasms, particularly when presenting as giant thoracic masses. We report a case of a 57-year-old woman with progressive chest pain and dyspnoea who initially presented with pleural effusion and hypoglycaemia and received empirical anti-tuberculosis therapy without improvement. Contrast-enhanced CT revealed a left lower lobe mass enlarging to 11 × 16.5 × 15.2 cm on repeat imaging, with rightward cardiac displacement, pericardial effusion and a hepatic nodule suspicious for metastasis to the liver. Core needle biopsy revealed a low-grade spindle cell neoplasm. Immunohistochemistry revealed diffuse STAT6 positivity, partial CD34 positivity, Ki-67 < 5%, and negativity for CK7, desmin, SMA and S100, supporting the diagnosis of SFT. Following a multidisciplinary evaluation, six cycles of systemic chemotherapy were administered, and the patient remained clinically stable. This case highlights the diagnostic challenges of giant intrapulmonary SFT and the pivotal role of STAT6 immunohistochemistry in establishing the diagnosis.