Clinical Application of Next-generation Sequencing for the Diagnosis of Lung Squamous Cell Carcinoma: Is It Primary or Secondary?

An 80-year-old man with a history of cutaneous squamous cell carcinoma (SCC) was referred to our department for a solitary lung nodule. The nodule was surgically resected and diagnosed as SCC. Because the lung lesion and a previous skin lesion showed similar histological findings, the origin of the lung tumor was uncertain. Next-generation sequencing using a targeted driver oncogene panel was applied for the further examination. The lung lesion was diagnosed as primary lung SCC, as the two tumors possessed distinct somatic mutations in TP53. Recent advances in clinical sequencing have enabled us to obtain an accurate diagnosis in pathologically challenging cases.