Clinicopathological review of solitary fibrous tumors: dedifferentiation is a major cause of patient death
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Solitary fibrous tumor (SFT) is a soft-tissue neoplasm of intermediate malignant potential, presenting a wide histopathological spectrum. Poorer prognosis of hemangiopericytoma of the central nervous system (CNS), hypoglycemic SFT, and dedifferentiation are well-known characters of SFT, but their clinical significance were not demonstrated enough by large-sized study. Here, the clinicopathological features of SFTs are reviewed and the relationship between genetics and clinicopathological features is examined using 145 SFT cases. All cases were STAT6 IHC-positive and/or NAB2-STAT6 fusion gene-positive. Tumor location was classified into three categories: 30 pleuropulmonary, 96 non-pleuropulmonary/non-central nervous system (CNS), and 18 CNS tumors. The tumor developed recurrence in 21 of 93 available cases (22.5%), metastasis in 11 of 93 (11.8%), and tumor death in 9 of 93 (9.6%). Hypoglycemia occurred in 2 primary tumors and 1 metastatic tumor among 63 reviewable cases, and dedifferentiation occurred in 10 cases (6.8%) including 6 primary tumors, 2 recurrent tumors, and 2 metastatic tumors. Recurrence was positively associated with CNS location (p = 0.0109) and hypoglycemia (p = 0.001); metastasis was positively associated with CNS location (p = 0.0231), hypoglycemia (p < 0.0001), and dedifferentiation (p < 0.0001), while metastasis was negatively correlated with pleural location (p = 0.0471). Tumor death was positively associated with male sex (p = 0.0154), larger size (p = 0.0455), hypoglycemia (p < 0.0001), and dedifferentiation (p < 0.0001). Multivariate analysis revealed independent statistical significance of dedifferentiation for overall survival (p = 0.0467). Exon variant of the fusion gene had no statistical correlation with clinical outcome. In conclusion, dedifferentiation is a major prognostic factor of SFT, and specific location such as cerebromeningeal and intra-abdominal site and hypoglycemia also had a high risk for unfavorable prognosis.
KeywordsSolitary fibrous tumor Hemangiopericytoma SFT STAT6 Dedifferentiated Hypoglycemia
Technical support for the experimental trials was provided by the following laboratory assistants: Motoko Tomita, Mami Nakamizo, Juri Godo, Miwako Ishii, Hisami Matsumoto, and Noriko Aoki. We also appreciate the technical assistance from staff at The Research Support Center, Kyushu University Graduate School of Medical Sciences.
Yuichi Yamada performed the research and wrote the paper. Kenichi Kohashi, Izumi Kinoshita, Hidetaka Yamamoto and Takeshi Iwasaki contributed to the research design and slide review. Shin Ishihara, Yu Toda, Yoshihiro Itou, Yutaka Koga, Mikiko Hashisako, Yui Nozaki, Daisuke Kiyozawa, Daichi Kitahara, Takeshi Inoue, Munenori Mukai, Yumi Honda, Gouji Toyokawa, Kenji Tsuchihashi, Yoshifumi Matsushita, Fumiyoshi Fushimi, Kenichi Taguchi, Sadafumi Tamiya, Yumi Oshiro, Masutaka Furue, Yasuharu Nakashima, Satoshi Suzuki, and Toru Iwaki contributed to the sample collection and research design. Yoshinao Oda designed the research and gave final approval of the manuscript. All authors critically reviewed and approved the manuscript.
This study was supported by a JSPS KAKEN Grant (No. 17K15645) and by funds from the Scholarship Program of the Takeda Science Foundation.
Compliance with ethical standards
This study was conducted in accordance with the principles embodied in the Declaration of Helsinki. The study was also approved by the Ethics Committee of Kyushu University (Nos. 25-111, 25-143). Informed consent was obtained from the subjects or guardians.
Conflict of interest
The authors declare that they have no conflicts of interest.
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