PDGFRA and neoplasm: Sanger sequencing of DNA from the flash-frozen tumor indicated that no mutations were present in the “hotspot” exons of KIT, PDGFRA, or BRAF. Exon-based sequencing of the SDH complex subunit genes SDHA-D identified no SDHX mutations, and the tumor was immunohistochemically positive for SDHB expression [20].