Solitary fibrous tumors (SFTs) are uncommon mesenchymal neoplasms that can arise in virtually any anatomical location [1]. First described in the pleura, they have since been reported in numerous extrathoracic sites, including the lung parenchyma [2].

In the thoracic cavity, most SFTs originate from the visceral or parietal pleura; purely intraparenchymal pulmonary SFTs without pleural attachment are exceedingly rare [3]. Their rarity and nonspecific radiologic appearance often challenge preoperative diagnosis, as they may mimic more common primary lung tumors or benign masses [4].

Although the majority of SFTs follow an indolent course, some exhibit aggressive features such as local recurrence, malignant transformation, or distant metastasis [4]. Prognostic factors, including tumor size, mitotic index, necrosis, and infiltrative growth, have been linked to unfavorable outcomes. The discovery of the NAB2-signal transducer and activator of transcription 6 (STAT6) fusion has advanced diagnostic accuracy, and nuclear STAT6 immunostaining is now considered a sensitive and specific marker for SFT [4, 5].

Complete surgical resection with negative margins remains the cornerstone of treatment because SFTs generally show limited response to chemotherapy or radiotherapy [6]. Long-term follow-up is recommended, as late recurrences or metastases may occur even in histologically benign cases [2, 6].

We report a case of a large SFT arising from the lung parenchyma and discuss the diagnostic and perioperative challenges in the context of current literature.

The timeline is listed in Table 1.

A 69-year-old woman with a history of pustular psoriasis on long-term corticosteroid therapy and a 20-pack-year smoking history presented with progressive exertional dyspnea. An SFT of the left lower lobe had been diagnosed by computed tomography (CT)-guided biopsy four years earlier, but surgery was initially deferred. Follow-up imaging showed marked tumor growth to approximately 15 × 14.5 × 12.5 cm (Figure 1, Figure 2A), leading the multidisciplinary tumor board to recommend resection.

On examination, she was overweight but in good general condition, with mild expiratory wheezing. Pulmonary function revealed forced expiratory volume in one second (FEV₁) of 1.17 L (46% predicted), but stair-climb and six-minute walk tests indicated sufficient functional reserve. Echocardiography showed preserved biventricular function with only trace mitral regurgitation. Preoperative bronchoscopy found no endobronchial involvement. Abdominal imaging identified multiple cystic pancreatic lesions consistent with side-branch intraductal papillary mucinous neoplasm (IPMN) without worrisome features. Endoscopic ultrasound confirmed the benign appearance of these lesions, and upper gastrointestinal endoscopy revealed only inflammatory and metaplastic changes without evidence of malignancy. The gastroenterology team recommended no intervention but follow-up imaging and carbohydrate antigen (CA) 19-9 and carcinoembryonic antigen (CEA) measurements in six months.

Given the substantial tumor size and the anticipated risk of intraoperative respiratory and hemodynamic compromise, detailed preoperative anesthetic planning was undertaken in collaboration with the cardiothoracic anesthesia team. Particular attention was paid to the possibility of impaired ventilation following induction due to mass effect and mediastinal shift. Double-lumen endotracheal intubation was performed to allow single-lung ventilation and optimize surgical exposure. Invasive hemodynamic monitoring, including arterial and central venous catheterization, was established prior to incision.

Because large thoracic SFTs may be associated with sudden cardiovascular instability or difficulty in maintaining adequate oxygenation, extracorporeal membrane oxygenation (ECMO) backup was discussed preoperatively with the perfusion team. Although ECMO was not ultimately required in this case, equipment and personnel were kept on standby to allow rapid deployment if severe intraoperative hypoxemia or hemodynamic collapse occurred.

Anesthetic induction and maintenance were conducted with careful titration to minimize cardiovascular depression, and close communication between the surgical and anesthesia teams was maintained throughout the procedure.

The patient underwent open left lower lobectomy with mediastinal lymphadenectomy (Figure 2B, Figure 3). She was extubated on the day of surgery but developed cardiopulmonary instability requiring re-intubation and cardiopulmonary resuscitation. She recovered with supportive care and was successfully extubated on postoperative day 5. A postoperative CT scan revealed a small peripheral pulmonary embolism in the right upper lobe artery; anticoagulation with apixaban was started. Postoperative histology confirmed the diagnosis of SFT (Figure 4).

Her subsequent course was marked by transient tachyarrhythmia managed with digoxin, effective diuresis, and empiric antibiotics for elevated inflammatory markers. Thoracic drains were removed uneventfully, and she was transferred to the surgical ward on postoperative day 12. She reported moderate chest pain attributed to resuscitation efforts, but cardiac ischemia was excluded. A postoperative pleural effusion (Figure 2C) was treated with diuretics.

The case was discussed both preoperatively and postoperatively in our institutional multidisciplinary thoracic oncology tumor board, which includes thoracic surgeons, medical oncologists, pulmonologists, radiologists, pathologists, radiation oncologists, and nuclear medicine specialists. Postoperative histopathological examination revealed an 18 cm SFT weighing 1,466 g, with focally increased mitotic activity, hypercellularity, and areas of tumor necrosis. Based on established risk stratification models, these features classified the tumor as high risk for recurrence and metastatic potential.

After a comprehensive review of the current literature and consideration of the complete (R0) resection status, the tumor board recommended structured long-term surveillance rather than adjuvant chemotherapy. This decision was based on the limited and inconclusive evidence supporting adjuvant systemic therapy in completely resected SFTs, even in high-risk cases. A follow-up strategy with regular cross-sectional imaging was therefore initiated, with planned surveillance for at least 10 years.

The remainder of her recovery was uneventful, and she was discharged on postoperative day 16 in stable condition with instructions for ongoing respiratory physiotherapy and laboratory follow-up. At the 3-month follow-up visit, the patient was in good general condition and reported marked improvement in dyspnea compared to her preoperative status. Physical examination was unremarkable. Follow-up contrast-enhanced chest CT showed no evidence of local recurrence, residual disease, or distant metastasis. Anticoagulation therapy for the postoperative pulmonary embolism was continued as planned, without complications. The patient remains under structured long-term radiologic surveillance according to tumor board recommendations.

The diagnostic tests and findings are listed in Table 2.

Following recovery from surgery, the patient reported a significant improvement in breathing and exercise tolerance compared with her preoperative condition. She expressed satisfaction with the surgical outcome and the multidisciplinary care provided. The patient agreed with the recommended long-term follow-up strategy and continues to participate in regular surveillance imaging.

SFTs are uncommon mesenchymal neoplasms that most frequently arise from the pleura but may occur virtually anywhere in the body, including the lung parenchyma [1–3, 6, 7]. Intraparenchymal pulmonary SFTs without pleural attachment are particularly rare and may be radiologically indistinguishable from other benign or malignant pulmonary masses [6, 7].

SFTs of the lung are rare and often present a diagnostic challenge due to their nonspecific clinical and radiologic features. Histopathologic confirmation with STAT6 immunohistochemistry remains essential for accurate diagnosis. Complete surgical resection with negative margins is the mainstay of treatment and offers the best chance for long-term disease control. However, because tumor size and other histologic factors can predict recurrence, long-term imaging surveillance is mandatory even for apparently benign lesions. Our case highlights the importance of early recognition, prompt surgical intervention, and multidisciplinary management to achieve optimal outcomes in these uncommon tumors.