RESUMEN
The incidence of neoplastic pulmonary embolism is certainly underestimated Necroscopy series report figures varying from 2.9 to 26. The clinical manifestations are similar to those observed in cruoric pulmonary embolism. We report two cases of acute respiratory failure with normal chest X-ray in which the diagnosis was neoplastic pulmonary embolism. The difficulties encountered for diagnosis resulted from the diffuse microvascular nature of the lesions. Perfusion scintigraphy and Swan-Ganz catheterism can be contributive, but certain diagnosis requires pathology examination. Prognosis is very poor. Clinicians should be aware of this pathology and entertain the diagnosis in all cor pulmonale patients with acute respiratory failure and a normal chest X-ray.