A Case of Pulmonary Tumor Thrombotic Microangiopathy Suggested by the Presence of Tumor Cells in Peripheral Blood

Pulmonary tumor thrombotic microangiopathy (PTTM) is characterized by tumor cell microemboli with occlusive fibrointimal remodeling in small pulmonary vessels. Platelet-derived growth factor (PDGF) has been implicated in the development of PTTM, and fibroblast growth factor (FGF) promotes PDGF signaling via PDGF receptor β. We here describe a cancer patient who presented with dyspnea of uncertain etiology and whose condition worsened rapidly. A 68-year-old man with hypopharyngeal squamous cell carcinoma (cT4aN2bM0, stage IVA) was treated with surgery followed by radiation. Two years later, a lung metastatic lesion was surgically removed on the basis of suspected primary lung cancer. The patient was thereafter monitored without chemotherapy. Two months later, he had third-degree burns and received conservative therapy including debridement and application of trafermin (FGF2) spray. Two weeks later, he was hospitalized with complaints of fever and dyspnea. Pneumonia and pulmonary embolism were ruled out by chest computed tomography with pulmonary arterio-graphy, whereas intravascular lymphoma was excluded by laboratory testing. Malignant cells were detected in his peripheral blood on hospital day 8, and their number increased gradually thereafter. His respiratory symptoms worsened, and the patient died on hospital day 10. We concluded that the cause of death was PTTM, with the clinical course suggesting a possible relation to trafermin. This suggestion was supported by the detection of FGF receptor 2 overexpression in the primary tumor by immunostaining.