Poorly differentiated chordoma with loss of SMARCB1/INI1 expression in pediatric patients: A report of two cases and review of the literature. Issue 1 (15th August 2017)

• Record Type: Journal Article
• Authors: Cha, Yoon Jin; Hong, Chang‐Ki; Kim, Dong‐Seok; Lee, Seung‐Koo; Park, Hyeon Jin; Kim, Se Hoon
• Is Part Of: Neuropathology. Volume 38:Issue 1(2018)
• Page Start: 47
• Page End: 53
• Publication Date: 2017-08-15
• Subjects: brachyury -- chordoma -- immunohistochemistry -- pediatrics -- SMARCB1/INI1; Nervous system -- Diseases -- Periodicals; Nervous system -- Pathophysiology -- Periodicals; 616.8047
• DOI: 10.1111/neup.12407
• Languages: English
• ISSNs: 0919-6544

Abstract

Abstract : Identification of loss of SMARCB1/INI1 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 SMARCB1/INI1 expression by inactivating mutation of the SMARCB 1/ INI gene. So far, around 20 cases of pediatric PD chordoma with loss of SMARCB1/INI1 expression have been reported. Here, we report two cases of pediatric PD chordoma with loss of SMARCB1/INI1 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 SMARCB1/INI1 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 SMARCB1/INI1 expression and positivity for nuclear brachyury staining, the final pathologic diagnosis for both cases was PD chordoma.