title: [Molecular genetics and immunophenotype of INI1/SMARCB in epithelioid sarcoma].
abstract: OBJECTIVE
  To study the immunophenotype and molecular genetics of epithelioid sarcoma (ES), INI1 expression and its role in differential diagnosis.
  
  
  METHODS
  Twenty cases of ES were retrieved from the archival files and selected for immunohistochemical study, DNA sequencing and fluorescence in-situ hybridization. The clinical and pathologic features were also reviewed.
  
  
  RESULTS
  The age of patients ranged from 16 to 75 years (mean = 40.2 years). The median age of patients in classic ES and proximal-type was 37.9 years and 42.0 years, respectively. The male-to-female ratio was 1.2: 1.0. Classic ES mostly occurred in the extremities while proximal-type ES often affected the perineum and external genitalia and trunk. Histologically, granuloma-like structures, consisting of aggregates of epithelioid and spindly tumor cells with central necrosis, were observed in classic ES. The epithelioid tumor cells contained abundant eosinophilic cytoplasm, merged with spindly cells at the periphery and admixed with collagen fibers. In proximal-type ES, the tumor cells showed prominent epithelioid and/or rhabdoid features, had marked cytologic atypia and grew in multinodular or diffuse patterns. In 2 cases of proximal-type ES studied, the "rhabdoid" tumor cells demonstrated a diffuse sheet-like growth pattern, mimicking malignant rhabdoid tumor. Immunohistochemical study showed that vimentin was positive in all cases. Pan-cytokeratin, CK8, CK7, epithelial membrane antigen and CD34 were expressed in 16, 15, 1, 18 and 13 cases, respectively. The staining for S-100 protein was focal and weak in 5 cases. None of the cases studied expressed CD31 and HMB45. Loss of INI1 was demonstrated in 10 of the 13 classic ES cases and 5 of the 7 proximal-type ES cases. The mutation of INI1 gene was detected in 1 of the 6 cases. Deletion of INI1 gene including heterozygous deletion, homozygous deletion and haploid was observed in 8 of the 11 cases.
  
  
  CONCLUSIONS
  Owing to the histologic heterogeneity, pitfalls in diagnosis of ES sometimes are encountered. INI1 is lost in most cases of ES. Immunohistochemical study, including staining for INI1, provides useful clues in pathologic diagnosis. Instead of INI1 mutation, inactivation of INI1 gene related deletion is not uncommon.
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China.
authors.forename: Qiuyuan
authors.initials: Q
authors.lastname: Xia
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China.
authors.forename: Qiu
authors.initials: Q
authors.lastname: Rao
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wu
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Shi
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yu
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China.
authors.forename: Rusong
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China.
authors.forename: Zhenfeng
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Department of Pathology, Medicine School of Nanjing University/Nanjing Jinling Hospital, Nanjing 210002, China. E-mail: zhouxj3456@163.com.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Zhou
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D017353:Gene Deletion; D006801:Humans; D016130:Immunophenotyping; D017404:In Situ Hybridization, Fluorescence; D007633:Keratins / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018396:Mucin-1 / Q000378:metabolism; D009154:Mutation; D018335:Rhabdoid Tumor / Q000235:genetics; D000071796:SMARCB1 Protein; D012509:Sarcoma / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D055815:Young Adult
chemical_list: D018952:Antigens, CD34; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D018396:Mucin-1; D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human; D014157:Transcription Factors; D007633:Keratins