An attempt was made to define the incidence of tumor metastasis to central bronchi that could clinically mimic primary bronchogenic carcinoma. In a retrospective review of 1,359 consecutive autopsies at Walter Reed General Hospital, metastatic involvement of a major airway was present in only 2% of patients who died with solid tumors. The most common extrathoracic tumors associated with metastatic involvement of a central airway are renal and colorectal carcinomas. The clinical and roentgenographic features of endobronchial metastasis and bronchogenic carcinoma were found to be indistinguishable. However, in the majority of cases the primary tumor site is clinically apparent before symptoms of endobronchial metastasis. In most cases of endobronchial metastasis, the histologic appearance of the bronchoscopic biopsy suggests the correct diagnosis. A central bronchogenic carcinoma should rarely be confused with a metastasis to a major airway from an extrathoracic source.
Braman SS, Whitcomb ME. Endobronchial Metastasis. Arch Intern Med. 1975;135(4):543-547. doi:10.1001/archinte.1975.00330040055008