Objective:

To describe the diagnosis and clinical course of a giant intrapulmonary solitary fibrous tumor (SFT) in a 57-year-old woman.

Approach:

• Diagnostic evaluation: The evaluation included serial contrast-enhanced CT, core needle biopsy, histopathology, and immunohistochemistry.
• Follow-up: Imaging and pulmonary function testing were used to assess the course after systemic chemotherapy.

Key Findings:

• The left lower lobe mass enlarged to approximately 16.5 cm and was associated with cardiac displacement, atelectasis, pericardial effusion, and a 3.8-cm hepatic nodule suspicious for metastasis.
• Biopsy showed a low-grade spindle cell neoplasm with 1–2 mitoses per 10 high-power fields and a Ki-67 index below 5%.
• Immunohistochemistry showed diffuse nuclear STAT6 and partial CD34 positivity, supporting an SFT diagnosis; CK7, desmin, smooth muscle actin, and S100 were negative.
• Upfront surgery was deferred because of extensive disease and suspected metastasis. After six chemotherapy cycles, imaging showed persistent tumor and suspected pericardial invasion; the patient remained clinically stable.
• Earlier hypoglycemia raised suspicion for Doege–Potter syndrome, but IGF-2 was not measured.

Interpretation:

The authors emphasized integrating clinical, radiologic, histopathologic, and immunohistochemical findings to diagnose giant intrapulmonary SFT and guide individualized management. They described nuclear STAT6 as a sensitive and specific marker for SFT, particularly in distinguishing it from other spindle cell neoplasms.

Limitations:

• A single case cannot establish diagnostic performance of immunohistochemical markers or chemotherapy effectiveness.
• The hepatic lesion was not histologically confirmed as metastatic.
• Without IGF-2 testing, Doege–Potter syndrome could not be confirmed.
• Persistent tumor burden limited conclusions about treatment response.

Conclusion:

The case involved a large intrapulmonary SFT with low-grade histologic features but extensive local involvement and suspected metastatic disease.

Sources:

• Respirology Case Reports (source named in provided context)