title: Histological spectrum of angiofibroma of soft tissue: histological and genetic analysis of 13 cases.
abstract: OBJECTIVE
  Angiofibroma of soft tissue (AFST) is a rare soft tissue neoplasm characterized by a fibroblastic cytomorphology and a prominent vascular structure. AFSTs possess a novel fusion gene, i.e. NCOA2-AHRR/AHRR-NCOA2 or GTF2I-NCOA2, providing a useful approach to diagnosing AFST. Morphologically, AFSTs span a wide spectrum, making diagnosis a challenge. The aim of this study was to review AFST cases and to report previously unknown histological features, which we confirmed by genetic analysis.
  
  
  RESULTS
  We reviewed 276 cases diagnosed as solitary fibrous tumours/haemangiopericytomas (232 cases), unclassified tumours of fibroblastic differentiation (36 cases), and recently diagnosed AFSTs (eight cases), and retrieved 13 cases compatible with AFST. Immunohistochemical staining was performed for these cases, all 13 of which were analysed by reverse transcription polymerase chain reaction and fluorescence in-situ hybridization. The histological findings were as follows: amianthoid fibres, extravasation of red blood cells, haemosiderin deposition, aggregates of foamy histiocytes, cystic change, necrosis, and haemorrhage. Immunohistochemically, the tumour cells were positive for epithelial membrane antigen (four of 13 cases), desmin (six of 13 cases), CD163 (13 of 13 cases), CD68 (seven of 13 cases), oestrogen receptor (13 of 13 cases), progesterone receptor (three of 13 cases), and STAT6 (one of 13 cases, weak nuclear staining), but they were negative for CD34, α-smooth muscle actin, muscle-specific actin, S100, pan-cytokeratin, MDM2, and CDK4. The AHRR-NCOA2 fusion gene was detected in eight cases, and NCOA2 gene rearrangement in nine cases.
  
  
  CONCLUSIONS
  We revealed the previously unreported histological variation and immunohistochemical findings of AFST, and confirmed them by using genetic methods. The results suggested that AFST should be considered in the diagnosis of fibrous or fibrohistiocytic tumours with the above histological features.
authors: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Yuichi
authors: Y
authors: Yamada
authors: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Hidetaka
authors: H
authors: Yamamoto
authors: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Kenichi
authors: K
authors: Kohashi
authors: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Takeaki
authors: T
authors: Ishii
authors: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Kunio
authors: K
authors: Iura
authors: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Akira
authors: A
authors: Maekawa
authors: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Hirofumi
authors: H
authors: Bekki
authors: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Hiroshi
authors: H
authors: Otsuka
authors: Department of Pathology and Biological Responses Graduate School of Medicine, Nagoya University, Nagoya, Japan.
authors: Kyoko
authors: K
authors: Yamashita
authors: Section of Oncopathology and Regenerative Biology, Department of Pathology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
authors: Hiroyuki
authors: H
authors: Tanaka
authors: Department of Human Pathology, Field of Oncology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors: Tsubasa
authors: T
authors: Hiraki
authors: Department of Pathology, Kouseiren Takaoka Hospital, Takaoka, Japan.
authors: Munenori
authors: M
authors: Mukai
authors: Department of Pathology, Sumitomo Besshi Hospital, Niihama, Japan.
authors: Atsuko
authors: A
authors: Shirakawa
authors: Department of Clinical Pathology, National Hospital Organization Okayama Medical Centre, Okayama, Japan.
authors: Yoko
authors: Y
authors: Shinnou
authors: Department of Diagnostic Pathology, Faculty of Medicine, University Hospital, Kagawa University, Kagawa, Japan.
authors: Mari
authors: M
authors: Jinno
authors: Department of Pathology, Okayama University Hospital, Okayama, Japan.
authors: Hiroyuki
authors: H
authors: Yanai
authors: Department of Pathology, National Kyushu Cancer Centre, Fukuoka, Japan.
authors: Kenichi
authors: K
authors: Taguchi
authors: Department of Surgery and Science, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
authors: Yoshihiko
authors: Y
authors: Maehara
authors: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Yukihide
authors: Y
authors: Iwamoto
authors: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Yosinao
authors: Y
authors: Oda
mesh_terms: D000328:Adult; D000368:Aged; D018322:Angiofibroma / Q000235:genetics* / Q000473:pathology*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D005260:Female; D015321:Gene Rearrangement; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D051958:Nuclear Receptor Coactivator 2 / Q000235:genetics; D050596:Oncogene Fusion / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012983:Soft Tissue Neoplasms / Q000235:genetics* / Q000473:pathology*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D051958:Nuclear Receptor Coactivator 2; D012097:Repressor Proteins; C492162:AHRR protein, human; C498001:NCOA2 protein, human
keywords: AFST; angiofibroma of soft tissue; fusion gene