Diagnostic challenges and treatment options in patients with solitary fibrous tumor: A single-center observational study

Abstract

Introduction: Solitary fibrous tumor (SFT) is an extremely rare disease with a high misdiagnosis rate and a potentially malignant biologic nature. We have collected and analyzed data from 18 SFT patients to provide a deeper insight into this uncommon disease entity.

Methods: In our study, 18 patients who had undergone surgery between April 2014 and December 2021 for the diagnosis of SFT were evaluated. The collected data for each patient included the location of the SFT, the preoperative diagnosis, the definitive histological diagnosis, the presence of postoperative complications, the time of recurrence, the time of systemic progression, the type of treatment, and the survival rate. The median follow-up was 36 months.

Results: In three patients, the preoperative diagnosis did not correlate with the definitive histology of SFT. In patients with the limb location of SFT, no signs of recurrence nor distant metastases were seen within the study period. In total, 50% of the postsurgical complications were associated with the abdominal location of the SFT. In newly diagnosed SFT patients, two patients (20%) developed local recurrence, and the median time until recurrence was 22.5 months. Out of patients that were admitted and operated on for recurrent SFT, 67% relapsed, and the median time to relapse was 9.5 months. The systemic progression of the disease was observed in 33% of patients treated for recurrent SFT.

Conclusion: In our study, the misdiagnosis rate was high and correlated with previously published studies. Postsurgical complications were associated with the extrathoracic location of SFT. The mainstay of SFT treatment remains radical surgery, although radiotherapy alone can significantly improve overall survival. Clinical trials are urgently needed to evaluate the potential effect of other treatment modalities, such as immunotherapy and targeted therapy, in SFT patients.

Keywords: SFT metastasis; SFT surgery; SFT surgical complications; SFT treatment; soft tissue sarcoma, pseudosarcomatous lesions, sarcoma misdiagnosis, solitary fibrous tumor recurrence.

Figure 1

Solitary fibrous tumor (SFT) and disease overlap. SFT often causes difficulties in diagnosis and treatment. Due to a clinicopathological overlap, misinterpretation of other diseases may lead to incorrect diagnoses in patients with SFT. The diseases displaying the most similar patterns to SFT are sarcoma, gastrointestinal stromal tumor (GIST), mesothelioma, desmoid, benign mesenchymal tumor, dermatofibrosarcoma protuberans, carcinoma, and pseudosarcomatous lesions.

Figure 2

Prognostic variables and selected observations of the study cohort. The upper left section is a schematic diagram presenting the proportions of patients with intrathoracic (78%), intra-abdominal (11%), and limb location (11%) of solitary fibrous tumor (SFT). The upper right section presents the age range and age median of the study cohort. The lower left section shows that systemic progression of the disease was observed in 33.33% of patients who underwent surgery for recurrent SFT and in 10% of patients with newly diagnosed SFTs. Patients that were admitted and operated on for recurrent SFT tended to relapse earlier. The lower right section is a schematic diagram presenting the number of patients with disease recurrence/systemic progression. Out of 10 patients surgically treated for primary SFT, 2 (20%) patients developed local recurrence, and 1 (10%) patient presented with the systemic progression of the disease. Out of 6 patients who were admitted and operated on at our department for local recurrence of SFT, 4 (66.67%) patients presented with another episode of local SFT recurrence after being surgically treated, and 2 (33.33%) patients developed metastases.

Figure 3

Clinical data heatmap. Eighteen patients underwent surgical treatment between April 2014 and December 2021 for the diagnosis of solitary fibrous tumor (SFT). Clinical data, including age, sex, tumor location, and disease recurrence/systemic progression, are visualized in a heatmap. The color intensity shows the magnitude of a selected phenomenon.

Figure 4

Time until disease recurrence. Patients with recurrent SFT (B) tended to relapse earlier (median 9.5 months, ranging from 5 to 19 months) than patients operated on for newly diagnosed SFT (A). The median time until disease recurrence in (A) patients was 22.5 months. SFT, solitary fibrous tumor.