Extraskeletal myxoid chondrosarcoma with rhabdoid features, with special reference to its aggressive behavior

The presence of rhabdoid cells has been reported in Various types of malignant neoplasms. Thirty-six cases of extraskeletal myxoid chondrosarcoma (EMC) were reviewed, and three of them revealed rhabdoid features. These cases contained cells having prominent eosinophilic globular cytoplasm, but were otherwise typical of EMC. Immunohistochemically, cytokeratin (CAM 5.2) was positive in three of 20 cases (15%), including two of the three with rhabdoid features. The rhabdoid cells were also immunostained with vimentin. The 5-year survival rate in the 26 cases with follow-up information was 73%, and the 10-year survival rate was 63%. The cases with rhabdoid features had a significantly poorer prognosis (p=0.0271). This study suggests that presence of rhabdoid features is a predictor of aggressive behavior in EMC, as it was shown to be in other mesenchymal neoplasms.