Pulmonary tumor embolism is an uncommon complication of solid tumors; it has been sporadically reported, among others, in renal, testicular, breast, gastric and liver carcinomas. Among these reported cases, a smaller percentage of patients have documented morbimortality directly attributable to the embolism, which makes its nosological assessment challenging compared to other forms of pulmonary embolism [1, 3, 4]. Taking account of these difficulties, antemortem prevalence is poorly established in the literature; nonetheless, autopsy series provided an epidemiological estimation, indicating that the incidence of tumor embolism among patient with solid malignancies ranged between 1% and 2.4% [5, 6].

Tumor embolism should be discussed in a cancer patient who has presented with acute dyspnea, respiratory distress or clinical signs of pulmonary hypertension. In our case, early suspicion has been triggered by tumoral invasion of internal iliac vein and the persistence of pulmonary embolism in spite of various anticoagulation regimens. The observation of the resistance to anticoagulant therapy or the development of new emboli during treatment has been noted in previous reports of tumor embolism. These factors should be regarded as major clues in distinguishing between thromboembolism and tumor embolism [2, 3].

To date, the contribution of medical imaging to diagnosis remains limited; although CT scans coupled with angiography can be used to diagnose proximal embolism with no major difference to thromboembolism, a retrospective study showed multifocal beading and dilatation of peripheral pulmonary arteries, principally in a subsegmental distribution and involving multiple lobes in patient with tumor emboli [7]. Lung ventilation-perfusion imaging has shown greater diagnostic utility, as perfusion defects caused by tumor emboli are characteristically multiple, symmetric, and more peripheral compared to thromboembolism defects [8].

The gold standard for diagnosis is based on pathological findings; the use of right heart catheterization and pulmonary vasculature cytology can confirm the tumoral nature of thrombus. In our case, the abundance of thrombi in the right cavities, pulmonary trunk and its branches facilitated the sampling process. Surgical biopsy is mostly based on pulmonary endarterectomy associated with thromboembolectomy; even if this procedure provides definite pathological diagnosis, it is associated with an increased operative risk, especially in these frail patients [3].

While treatment of thromboembolism occurring in patients with active tumors is well-established [9], therapeutic options for tumor embolism remain limited, taking into account the dual high risks, thrombotic and hemorrhagic. Therapy of the primary tumor is often considered the management cornerstone, including surgery, chemotherapy or chemo-radiotherapy. However, patient outcomes are primarily contingent on tumor extension, malignancy, and its receptivity to chemotherapy [2].