Lung cancer is the most common and most lethal cancer worldwide. Its prognosis remains poor: The 5-year survival rate is 6-18%. Adenocarcinoma has surpassed squamous cell carcinoma as the leading histologic type, accounting for 30% of all cases of lung cancer. Hematogenous spread (i.e., carried by blood) is the most common mechanism of intrapulmonary metastasis. Although local venous spread can occur, systemic spread with secondary lung involvement is much more common.
“Cumulative evidence suggests that intrapulmonary aerogenous spread may exist and is underrecognized,” say the authors of “Aerogenous Metastases: A Potential Game Changer in the Diagnosis and Management of Primary Lung Adenocarcinoma,” published in the December 2014 issue of the American Journal of Roentgenology. “Aerogenous metastases must be differentiated from multiple synchronous lesions in the spectrum of lung adenocarcinoma, [and] imaging features are helpful in differentiating possible aerogenous spread of tumor.”
source : http://www.sciencedaily.com/releases/2014/12/141230101915.htm