P1.02-066 Genomic Profiling in the Differential Diagnostics of Pulmonary Tumors: A Case Series

Abstract

Histopathological diagnosis is important for prognostication and choice of treatment in patients with cancer in the lung. Lung metastases are common and need to be distinguished from primary lung cancer. Furthermore, cases with synchronous or metachronous primary lung cancers (although infrequent) are often handled differently than cases with lung cancer with intrapulmonary metastasis or relapse, respectively. In some cases, morphology and immunohistochemical (IHC) staining is not sufficient for certain diagnosis. Five cases were selected where molecular genetic analysis in form of pyrosequencing or targeted next-generation sequencing (NGS) was of value, not only for treatment prediction, but for certain diagnosis of tumors in the lung. Two of the included cases were rare metastases to the lung – rectal cancer with IHC profile consistent with primary lung cancer and malignant myoepithelioma of the breast, respectively – where molecular genetic analysis was of aid for proving the relationship with the primary tumor. The other three cases had multiple lung adenocarcinomas with similar morphology where molecular genetic analysis was of aid to distinguish between an intrapulmonary metastasis and a synchronous primary tumor. Comparison of molecular genetic profile may be an important tool for determination of relationship between tumors, at least in some situations, and should always be considered in unclear cases. Further studies on concordance and discordance of molecular genetic profiles between spatially or temporally different tumors with common origin may be helpful for improved diagnostics of pulmonary tumors.