Extraskeletal Myxoid Chondrosarcomas are not Characterized by Loss of INI1/SMARCB1: Immunohistochemical Analysis of 16 Cases

Abstract

Background: Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma, characterized by t (9; 22) translocation, including EWSR1 and NR4A3 gene rearrangements, observed in most cases. On histopathologic examination, an EMC has certain diagnostic mimics, such as myoepithelial tumors, epithelioid malignant peripheral nerve sheath tumor and epithelioid sarcomas. All these tumors are included in the category of INI1/SMARCB1-deficient tumors. Lately, few studies have shown loss of INI1 in certain EMCs. Considering there is preclinical data regarding role of EZH2 inhibitor in "INI1 deficient" tumors, it is crucial to recognize such tumors.