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
