Atypical teratoid/rhabdomyoid tumor:a clinicopathologic analysis of five cases

ZHANG Tong; LI Chun-mei; WANG Li-hua; REN Yu-bo; ZHONG Yan-feng

doi:10.3969/j.issn.1007-8096.2023.08.012

Abstract：Objective To investigate the atypical teratoid/rhabdomyoid tumor(AT/RT)of the clinical pathological features,immune phenotype analysis,diagnosis and differential diagnosis and its biological behavior and prognosis.Methods Five AT/RT5 cases diagnosed in Peking University International Hospital from December 2015 to December 2019 were collected,their clinical and imaging manifestations were observed,their histological,immunohistochemical and molecular genetic characteristics were analyzed,follow-up result were collected,and relevant literature was reviewed.Results In all the 5 cases,different striated muscle-like differentiation regions and small-cell embryonic components were observed.Different degrees of epithelioid differentiation,mesenchymal differentiation and spindle cell interstitial differentiation were seen,and even adenoid papillary arrangement was noted.In some cases,vascular endothelial cell hyperplasia and lamellar necrosis were also observed.The expression of SMARCB1(INI 1)was absent in all 5 cases,while the expression of SMARCA4(BRG1)was positive.GFAP,EMA,Vimentin,CD34,S100 and CK were expressed to different degrees in the tumor,and the Ki-67 proliferation index was high,up to 80％.Four patients died within 3 months after surgery,and one survived for 15 months.Conclusion AT/RT is a kind of embryonal malignant tumor that tends to occur in young children.It is highly invasive and has a poor prognosis,accompanied by rhabdomyoid differentiation and differentiation of primitive neuroectoderm,mesenchymal and epithelial cells.Most of them are accompanied by SMARCB1(INI1)expression loss,and a few are accompanied by SMARCA4(BRG1)expression loss,and differentiation from other central nervous system tumors is required.