Pulmonary Tumor Embolism

Abstract

We thank Shigematsu et al. for drawing our attention on the entity of pulmonary tumor thrombotic microangiopathy (PTTM) that was first described by von Herbay et al.1von Herbay A Illes A Waldherr R Otto HF Pulmonary tumor thrombotic microangiopathy with pulmonary hypertension.Cancer. 1990; 66: 587-592Crossref PubMed Scopus (239) Google Scholar These authors pointed out that the morphologic findings are different in PTTM and pulmonary tumor embolism (PTE), as illustrated by the comparison of their cases and those of previous descriptions. PTTM is characterized by activation of the coagulation cascade induced by tumor cells in the lung vasculature, resulting in obstructive thrombosis and intimal proliferation. PTE was described by Winterbauer et al.2Winterbauer RH Elfenbein IB Ball Jr, WC Incidence and clinical significance of tumor embolization to the lungs.Am J Med. 1968; 45: 271-290Abstract Full Text PDF PubMed Scopus (193) Google Scholar as pulmonary vascular obstruction by tumor emboli. In our case report,3Kridel R Myit S Pache JC Gaspoz JM Pulmonary tumor embolism: a rare cause of acute right heart failure with elevated D-dimers.J Thorac Oncol. 2008; 3: 1482-1483Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar the lung histology revealed that, whereas most of small lung arteries were entirely occluded with tumor emboli, only a minority of vessels was affected both by tumor emboli and thrombi. We therefore believe that our case report is compatible with descriptions of PTE rather than PTTM, despite the elevated d-dimer level. We doubt that the distinction between the two entities can currently be established in a clear-cut manner. Indeed, Kane et al.4Kane RD Hawkins HK Miller JA Noce PS Microscopic pulmonary tumor emboli associated with dyspnea.Cancer. 1975; 36: 1473-1482Crossref PubMed Scopus (183) Google Scholar have reported that tumor emboli to the lung vasculature are frequently associated with thrombi and later descriptions of PTE also highlighted that thrombosis and intimal proliferation often accompany tumor emboli.5Bassiri AG Haghighi B Doyle RL Berry GJ Rizk NW Pulmonary tumor embolism.Am J Respir Crit Care Med. 1997; 155: 2089-2095Crossref PubMed Scopus (77) Google Scholar, 6Roberts KE Hamele-Bena D Saqi A Stein CA Cole RP Pulmonary tumor embolism: a review of the literature.Am J Med. 2003; 115: 228-232Abstract Full Text Full Text PDF PubMed Scopus (177) Google Scholar Further research seems thus necessary to refine the diagnostic criteria of both entities.