Dedifferentiated Chordoma Harboring a Novel KRAS (G13D) Hot Spot Missense Mutation and an Additional Novel...

Dedifferentiated chordoma (DDC) is a rare subtype of chordoma, having a biphasic appearance, and is characterized by conventional chordoma juxtaposed with a high-grade sarcoma. The high-grade component varies from pleomorphic to fibrosarcomatous type. Several studies have been published in the literature highlighting the genetic mutations associated with conventional and poorly differentiated chordoma, however only one study has been published in the literature that included four cases of DDCs and has shown genetic alterations in p53, PTEN, RB, CDKN2A, and TERT promoter genes. There is no further molecular data available regarding DDCs. Hence, we have tried sequencing in our case of DDC which included 109 sarcoma-related genes covering all SNVs, insertions-deletions, and fusions. In our case, it is found to have a G13D mutation in the KRAS gene and a novel RPSAP52-HMGA2 fusion. Though, the clinical significance of these alterations is yet to be proven, it may help to better understand this entity.