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Poorly differentiated chordoma with loss of SMARCB 1/ INI 1 expression in pediatric patients: A report of two cases and review of the literature
Author(s) -
Cha Yoon Jin,
Hong ChangKi,
Kim DongSeok,
Lee SeungKoo,
Park Hyeon Jin,
Kim Se Hoon
Publication year - 2018
Publication title -
neuropathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.701
H-Index - 61
eISSN - 1440-1789
pISSN - 0919-6544
DOI - 10.1111/neup.12407
Subject(s) - brachyury , smarcb1 , chordoma , pathology , atypical teratoid rhabdoid tumor , immunohistochemistry , cancer research , medicine , biology , gene expression , gene , genetics , embryonic stem cell , chromatin remodeling , mesoderm
Identification of loss of SMARCB 1/ INI 1 expression in poorly differentiated ( PD ) chordoma in pediatric patients suggests that PD chordoma is an entity molecularly distinct from conventional chordoma or atypical teratoid/rhabdoid tumor, which is also characterized by loss of SMARCB 1/ INI 1 expression by inactivating mutation of the SMARCB 1/ INI gene. So far, around 20 cases of pediatric PD chordoma with loss of SMARCB 1/ INI 1 expression have been reported. Here, we report two cases of pediatric PD chordoma with loss of SMARCB 1/ INI 1 expression, which is very rare among the pediatric chordoma types. Both patients presented clival masses on preoperative MRI . Histologically, both tumors had nonclassic histologic features for conventional chordoma: sheets of large epithelioid to spindle cells with vesicular nuclei and prominent nucleoli. Both cases revealed nuclear expression of brachyury, loss of SMARCB 1/ INI 1 expression and lack of embryonal, neuroectodermal, or epithelial component. One case showed heterozygous loss of EWSR 1 gene by break‐apart fluorescence in situ hybridization that reflected loss of SMARCB 1/ INI1 gene. Based on the clival location and histologic findings along with the loss of SMARCB 1/ INI 1 expression and positivity for nuclear brachyury staining, the final pathologic diagnosis for both cases was PD chordoma.