Rare Giant Lung Tumour With Suspected Liver Spread Challenges Diagnosis and Treatment

A tumour so large that it pushed a patient’s heart to the right side of her chest is drawing attention to one of the rarest corners of lung pathology. In a case report published in Respirology Case Reports, physicians describe a 57-year-old woman found to have a giant intrapulmonary solitary fibrous tumour, an exceptionally uncommon mesenchymal neoplasm that arose not on the lung’s outer lining, where these tumours usually develop, but deep within the lung tissue itself. The mass ultimately measured more than 16 centimetres across its longest axis, and imaging revealed a nodule in the liver that physicians suspected was a metastasis, a finding that would place the tumour in the rare category of potentially malignant intrapulmonary solitary fibrous tumours with distant spread.

Solitary fibrous tumours are spindle cell neoplasms of mesenchymal origin, meaning they arise from connective tissue cells rather than from the epithelial cells that give rise to the vast majority of lung cancers. Most solitary fibrous tumours of the chest originate from the pleura, the thin membrane enveloping the lungs, and they are typically slow-growing and benign. When they occur inside the lung parenchyma instead, they become a genuine clinical curiosity. Published analyses suggest these intrapulmonary tumours most often affect adults between 50 and 70 years of age, and a clinicopathological review of 52 cases found a mean age of onset of 52.7 years, with the left lower lobe being the most frequently affected pulmonary location. That detail matters here, because the tumour in this new case arose in precisely that region.

The patient’s story began seven months before her definitive diagnosis, when a left-sided pleural effusion, an accumulation of fluid around the lung, was discovered incidentally during a hospital admission for hypoglycaemia. She had a history of diabetes mellitus, passive exposure to tobacco smoke, and more than two decades of employment in a textile factory. Initial chest radiography showed a homogeneous opacity in the left lower lung field accompanied by the effusion. Because tuberculosis remains a leading cause of pleural disease in many parts of the world, her physicians administered an empirical two-month course of anti-tuberculosis treatment. It failed. The opacity did not budge, a signal that something other than infection was occupying her chest.

Contrast-enhanced computed tomography performed in July 2025 finally revealed the true scale of the problem: a large mass in the left lower lobe measuring 14.1 by 15.6 by 12.1 centimetres. The patient was then lost to follow-up for more than five months, and when she returned with worsening chest pain and shortness of breath, repeat imaging showed that the tumour had grown to 11 by 16.5 by 15.2 centimetres. The mass was displacing her heart toward the right side of her chest, causing collapse of portions of the surrounding lung, and was accompanied by both pericardial and pleural effusions. Most ominously, a 3.8-centimetre nodule had appeared in the liver, suspicious for metastasis. Under the standard tumour-node-metastasis framework, the findings were classified as T4N0M1b, indicating a locally advanced tumour with possible distant spread but no involved lymph nodes.

A core needle biopsy of the mass yielded the tissue that would settle the diagnosis. Under the microscope, pathologists saw a low-grade spindle cell neoplasm with only one to two mitoses per ten high-power fields, a measure of how actively the cells were dividing. The decisive evidence came from immunohistochemistry, the technique that uses antibodies to detect specific proteins in tissue sections. The tumour cells showed diffuse nuclear positivity for STAT6, partial positivity for CD34, and a Ki-67 proliferation index below 5 percent, while staining for CK7, desmin, smooth muscle actin and S100 was negative. Diffuse nuclear STAT6 expression is regarded as a highly sensitive and specific marker for solitary fibrous tumours, reflecting the characteristic NAB2-STAT6 gene fusion that drives these neoplasms, and it is particularly valuable for distinguishing them from the many other spindle cell tumours that can arise in the chest.

The size of this tumour alone sets it apart. Radiologically, pulmonary solitary fibrous tumours typically present as well-circumscribed soft-tissue masses, and the majority of reported tumours measure less than 10 centimetres. A comparable giant presentation was described in a 2025 case report, in which a mass measuring 14 by 12 by 23 centimetres caused compressive atelectasis and raised concern for hepatic and splenic metastases. The combination in the current patient of massive tumour burden, compressive effects on the heart and mediastinum, suspected pericardial involvement and possible distant spread represents an unusually aggressive-looking profile for a tumour whose microscopic features still looked comparatively indolent.

One intriguing thread in the case is the patient’s earlier episode of hypoglycaemia. Solitary fibrous tumours are among the rare neoplasms capable of secreting insulin-like growth factor 2, a hormone-like protein that can drive blood sugar to dangerously low levels. This paraneoplastic phenomenon is known as Doege-Potter syndrome, and fewer than 2,000 cases have been reported worldwide. The connection is more than a medical curiosity: in a patient with a known fibrous tumour, unexplained hypoglycaemia can be a clue to the tumour’s biology, and resection of the tumour typically abolishes the metabolic derangement. In this case, however, serum IGF-2 levels were never measured, so the physicians could not formally confirm that the earlier hypoglycaemic episode was tumour-driven, leaving the association suggestive but unproven.

Pathologists weigh several features when judging whether a solitary fibrous tumour is likely to behave badly. Size greater than 10 centimetres, necrosis, increased mitotic activity, hypercellularity and nuclear pleomorphism all raise concern for malignant behaviour. The present tumour sailed past the size threshold and had radiographic evidence of possible metastasis, yet its mitotic count and Ki-67 index pointed toward low-grade histology. This tension between benign-looking cells and clinically ominous behaviour is precisely what makes solitary fibrous tumours so difficult to manage, and it underscores why diagnosis cannot rest on any single test. The authors emphasise that integrating clinical findings, imaging, histopathology and immunohistochemistry is essential to reaching an accurate diagnosis and tailoring treatment to the individual patient.

For localized solitary fibrous tumours, complete surgical resection remains the treatment of choice, and long-term survival after clean excision is generally excellent. But in this patient, a multidisciplinary team concluded that the extent of disease and the suspicion of metastatic spread made upfront surgery too risky. Systemic therapy became the pragmatic alternative, even though the evidence base for chemotherapy in advanced solitary fibrous tumours remains thin. Anthracycline-based regimens are commonly employed in unresectable or metastatic cases, and targeted approaches, including combinations of temozolomide with bevacizumab and the kinase inhibitors pazopanib and sunitinib, have shown promising results in refractory disease. The patient received six cycles of a four-drug regimen combining doxorubicin, cisplatin, vincristine and cyclophosphamide.

Follow-up imaging after chemotherapy showed a persistent mass measuring 16.2 by 9.0 by 14.7 centimetres with suspected invasion of the pericardium, the sac surrounding the heart, but no mediastinal lymphadenopathy. Pulmonary function testing revealed mild impairment of the lung’s diffusing capacity, with a DLCO of 67 percent of predicted, while standard spirometry was preserved. Clinically, the patient remained stable. The case, reported by Desdiani Desdiani and colleagues, is a reminder that even in an era of sophisticated imaging and molecular diagnostics, the rarest tumours still test the limits of clinical intuition. A mass that mimics tuberculosis, grows to the size of a small melon, shifts the heart within the chest and seeds a suspicious lesion in the liver demands that physicians hold every diagnostic tool in view at once, and that pathologists, radiologists and oncologists work in close concert to chart a course through genuinely uncharted territory.

Subject of Research: A rare giant intrapulmonary solitary fibrous tumour with suspected liver metastasis

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

Article References: Desdiani, D., Siregar, N. C., Prawiro, A., & Syahbunan, K. K. C. (2026). Giant Intrapulmonary Solitary Fibrous Tumour With a Possible Liver Metastasis: A Rare Case. Respirology Case Reports, 14(10), Article e70754. https://doi.org/10.1002/rcr2.70754

Image Credits: AI Generated

DOI: 10.1002/rcr2.70754

Keywords: solitary fibrous tumour, intrapulmonary tumour, STAT6, lung cancer, Doege-Potter syndrome, metastasis, immunohistochemistry, chemotherapy, case report, rare disease, spindle cell neoplasm, pleural effusion