RESUMO
Lung is known as a vulnerable organ to metastatic tumors. Metastasis occurs mainly through lymphatics but seldom via blood vessels. Adenocarcinoma with mucin emboli is very rare. Primary foci reported in the literature were breast, lung, ovary and pancreas. A lung biopsy from a 60-year-old male patient showed floating mucin associated with metastatic adenocarcinoma to the lung in the blood vessels. The tumor cells spreaded along the vascular endothelium as if they were vascular endothelial cells. The tumor cells and mucin in the vessel were strong positive for PAS staining. Elastic and immunohistochemical staining for smooth muscle actin highlighted the vascular wall in the mucin containing structure with infarction of the lung. The primary focus was identified in the pancreatic head through the abdominal ultra-sonographic and computer-tomographic examination.