KRAS G12S Positive Non-Small Cell Lung Cancer Mimicking KRAS G12C Positivity on the AmoyDx PCR Panel: A Case Report.

A false-positive KRAS G12C on a multi-PCR assay using the amplification refractory mutation system can potentially occur in cases harboring certain multi-nucleotide variants other than KRAS G12C. A 62-year-old man with a large left upper lobe tumor was diagnosed with lung adenocarcinoma. A multi-PCR assay by the AmoyDx Pan Lung Cancer PCR panel showed positivity for KRAS G12C and KRAS G12A/G12V/G12R/G13C. However, next-generation sequencing revealed a KRAS variant of c.34_35delinsTC (p.G12S). KRAS G12S multi-nucleotide variants may lead to false-positive KRAS G12C results on the multi-PCR assay.