Abstract
BACKGROUND: Sarcomatoid cancer is defined by the World Health Organization as a category of non-small cell lung cancers with sarcoma or sarcoma-like differentiation. They are characterized by poor prognosis and resistance to conventional chemotherapy. However, the mutational profile of sarcomatoid cancer remains yet to be elucidated. Sarcomatoid cancers are usually biphasic tumors composed of carcinomatous and sarcomatous components, but the evolutional development of sarcomatoid cancer is controversial. CASE PRESENTATION: We present an illustrative case of sarcomatoid cancer composed of three different histological areas. Targeted sequencing of 53 lung cancer-related genes was performed in each component and their phenotypic changes were correlated with stepwise addition of genetic changes. CONCLUSION: Sarcomatous change of carcinoma occurs in the case of sarcomatoid cancer, and phenotypic changes to sarcomatoid cancer are associated with the addition of mutation patterns and derived from poorly differentiation tumor.