Imaging description

There are two forms of intravascular tumor emboli:

1. Focally dilated and beaded pulmonary arteries on CT [1], resulting from clumps of tumor cells that become lodged within the lumen of small pulmonary arteries, and result in obstruction of the arteries, similar to bland thromboemboli (Figure 56.1).

2. Tree-in-bud pattern on high-resolution CT (representing prominence of otherwise inconspicuous small peripheral pulmonary arteries), resulting from either minute tumor emboli causing prominent fibrocellular proliferation of the intima with resulting thrombosis and luminal obliteration (thrombotic microangiopathy) [2], or filling of the centrilobular arteries with tumor cells themselves (Figures 56.2 and 56.3).

Importance

Pulmonary intravascular tumor emboli are seen in up to 26% of autopsies [3] but are much less frequently identified prior to death. Common extrapulmonary malignancies that cause pulmonary tumor emboli include hepatocellular, breast, renal, stomach and prostate, and choriocarcinoma [4]. Occasionally, this can be the presenting feature of neoplastic disease. The diagnosis of pulmonary endovascular choriocarcinoma in young female patients is of particular importance because it is potentially curable with chemotherapy [5].