title: A case of dedifferentiated solitary fibrous tumor of the thoracic cavity.
abstract: Solitary fibrous tumors (SFTs), initially observed in the pleura, were later found to develop in almost any extrapleural site. Dedifferentiation within SFTs, a rare phenomenon, was characterized only recently, although it was previously described in soft tissue and bone tumors. We report a case of dedifferentiated SFT arising in the right pleura of a 69-year-old man. Computed tomography revealed a huge mass in the thoracic cavity. The tumor contained an area with a high degree of calcification and was heterogeneously enhanced. Macroscopically, the resected tumor was 175×145×135 mm in size. Morphologically and immunohistochemically, this was comprised of a typical SFT juxtaposed to a high-grade component including an osteosarcomatous component. These were sharply demarcated by thin fibrous septa. Furthermore, NAB2-STAT6 fusion transcripts were detected by reverse-transcriptase polymerase chain reaction in both conventional and high-grade components, supporting the concept of a dedifferentiation process in this tumor.
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Masuda
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Aiko
authors.initials: A
authors.lastname: Kurisaki-Arakawa
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kieko
authors.initials: K
authors.lastname: Hara
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Arakawa
authors.affiliation: Department of General Thoracic Surgery, Juntendo University School of Medicine 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Shiaki
authors.initials: S
authors.lastname: Oh
authors.affiliation: Department of General Thoracic Surgery, Juntendo University School of Medicine 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yao
authors.affiliation: Department of Human Pathology, Juntendo University School of Medicine 2-1-1, Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Saito
mesh_terms: D000368:Aged; D054337:Cell Dedifferentiation; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054364:Solitary Fibrous Tumors / Q000473:pathology*; D035423:Thoracic Cavity / Q000473:pathology; D013899:Thoracic Neoplasms / Q000473:pathology*
keywords: NAB2-STAT6; Solitary fibrous tumor; dedifferentiation