The thorax is a common site for metastases from a wide spectrum of primary malignant tumors from different lineages. The microscopic appearance and genetic profile are those to the primary tumors. Molecular profile of the metastatic tumor and comparison with any primary tumor (if available) is desirable.  Metastases can manifest as single or multiple nodules/masses, Prognosis depends on primary disease and whether a single metastasis or multiple metastases can be surgically removed.

Metastases from germ cell tumors and some sarcomas are diagnosed mostly in young adults and children, while metastatic carcinomas are generally seen in older adults. 

Common sources of pleural metastases are lung adenocarcinoma and hematolymphoid neoplasms in men and invasive breast carcinoma, Müllerian carcinomas, and lung adenocarcinoma in women. Patients with pleural metastases may also develop a malignant effusion. 

The pericardium is the most frequently involved site of cardiac metastasis. Cardiac metastases are most often found in patients with multiple metastases and disseminated disease, and are more common than primary cardiac tumors.