Rarely a patient with cancer may develop symptoms secondary to numerous tumor microemboli lodging in small pulmonary blood vessels.


Tumor microemboli can be seen with many types of cancer, including

(1) breast

(2) stomach

(3) lung

(4) liver

(5) pancreas

(6) prostate


Clinical features:

(1) history of dyspnea on exertion

(2) cough

(3) chest and/or abdominal pain

(4) variable ascites

(5) variable peripheral edema

(6) may show subacute pulmonary hypertension with elevated pressures


Imaging studies:

(1) may have a normal chest X-ray or may show metastatic lung nodules

(2) absence of large pulmonary emboli

(3) may show cardiomegaly

(4) may show prominent pulmonary vasculature

(5) ventilation-perfusion scanning may show numerous, symmetrical and peripheral mismatched defects

(6) CT scan may be normal or show subtle changes in peripheral pulmonary arteries. The dilated septa associated with lymphangitic spread are typically absent.


Laboratory findings:

(1) hypoxemia

(2) respiratory alkalosis

(3) tumor cells in blood aspirated from the pulmonary artery with a wedged catheter


Differential diagnosis:

(1) drug-induced pulmonary toxicity

(2) interstitial fibrosis

(3) other forms of pulmonary emboli, including microclots

(4) infection

(5) lymphangitic tumor spread


To read more or access our algorithms and calculators, please log in or register.