title: Primary pleuropulmonary and mediastinal synovial sarcoma: a clinicopathologic and molecular study of 26 genetically confirmed cases in the largest institution of southwest China.
abstract: BACKGROUND
  Primary pleuropulmonary and mediastinal synovial sarcomas (PPMSSs) are extremely rare. The authors present the largest series in an Asian population.
  
  
  METHODS
  Between 2000 and 2015, 26 genetically confirmed PPMSSs were included. The clinicopathologic features of all of the cases were reviewed. Immunohistochemical staining was carried out using the following antibodies: TLE1, cytokeratin (AE1/AE3), EMA, CD99, Bcl-2, CK7, CD34, S-100 protein, and Ki-67. The chromosomal translocation t(X;18)(p11.2;q11.2) was detected by fluorescence in situ hybridization (FISH) and reverse transcription polymerase chain reaction (RT-PCR). We compared the clinical, pathologic, immunohistochemical, and molecular features of this series with that of the previous series and soft tissue synovial sarcomas.
  
  
  RESULTS
  This series included 17 males and nine females. The median age was 36.5 years (range, 16-72 years). The tumors involved the lung (76.9 %), pleura (15.4 %), and mediastinum (7.7 %). The median tumor size was 6 cm (range 2.3 ~ 24 cm). The majority of the tumors were well-circumscribed. The tumors were classified as monophasic (84.6 %), biphasic (3.8 %), and poorly differentiated (11.5 %) types. The tumors were graded as French Federation of Cancer Centers (FNCLCC) grade 2 (62.5 %) and FNCLCC 3 (37.5 %). Diffuse immunostaining for TLE1, BCL-2, and CD99 was identified in 91.7, 95.7, and 56.0 % of the tumors, respectively. Focal positivity was seen with EMA (84.6 %), CK7 (55.6 %), cytokeratin (AE1/AE3) (68.0 %), CD34 (5.0 %), and S-100 protein (21.7 %). A high Ki-67 index (≥10 %) was observed in 91.3 % of the tumors. The fusion transcripts included SS18-SSX1 (15/22, 68.2 %), SS18-SSX2 including variants (6/22, 27.3 %), and SS18-SSX4 (1/22, 4.5 %) fusions. The remaining four cases showed positivity for SS18 rearrangement by FISH. Surgical excision of tumors or lobectomy were performed in 20 patients, and seven of the patients underwent adjuvant therapy. Clinical follow-up was available in 73.1 % cases, with a median follow-up of 12.0 months. The median survival time was 14.5 months. Tumor resection (p = 0.024) and no residual tumor (p = 0.004) were associated with an improved overall survival time.
  
  
  CONCLUSIONS
  PPMSS is a highly aggressive neoplasm. Extensive surgical resection of the tumor and more effective adjuvant therapy should be advocated. PPMSS must be differentiated from similar diseases.
authors.affiliation: Department of Pathology, West China Hospital, Sichuan University, Guoxuexiang 37, 610041, Chengdu, Sichuan, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Lan
authors.affiliation: Department of Pathology, West China Hospital, Sichuan University, Guoxuexiang 37, 610041, Chengdu, Sichuan, China.
authors.forename: Huijiao
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Pathology, West China Hospital, Sichuan University, Guoxuexiang 37, 610041, Chengdu, Sichuan, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Xiong
authors.affiliation: Department of Pathology, Mianyang People's Hospital, Mianyang, Sichuan, China.
authors.forename: Tingqing
authors.initials: T
authors.lastname: Zhou
authors.affiliation: Department of Pathology, West China Hospital, Sichuan University, Guoxuexiang 37, 610041, Chengdu, Sichuan, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Peng
authors.affiliation: Department of Pathology, West China Hospital, Sichuan University, Guoxuexiang 37, 610041, Chengdu, Sichuan, China.
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.affiliation: Laboratory of Pathology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Ye
authors.affiliation: Department of Radiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Yao
authors.affiliation: Department of Pathology, West China Hospital, Sichuan University, Guoxuexiang 37, 610041, Chengdu, Sichuan, China.
authors.forename: Xin
authors.initials: X
authors.lastname: He
authors.affiliation: Department of Pathology, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan, China.
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Pathology, West China Hospital, Sichuan University, Guoxuexiang 37, 610041, Chengdu, Sichuan, China. hy_zhang@scu.edu.cn.
authors.forename: Hongying
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D002681:China; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008479:Mediastinal Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics* / Q000378:metabolism; D008482:Mediastinum / Q000473:pathology; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics; D015514:Oncogene Proteins, Fusion; D010994:Pleura / Q000378:metabolism / Q000473:pathology; D010997:Pleural Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D013584:Sarcoma, Synovial / Q000000981:diagnostic imaging / Q000235:genetics* / Q000378:metabolism; D014178:Translocation, Genetic; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D015514:Oncogene Proteins, Fusion; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; C093961:SS18 protein, human; C093962:synovial sarcoma X breakpoint proteins
keywords: Mediastinum; Pleuropulmonary; Prognosis; SS18-SSX fusion transcript; Synovial sarcoma