骨髄増殖性疾患に続発した慢性血栓塞栓性肺高血圧症の１例

A woman in her ６０s presented with shortness of breath on exertion and was admitted to a nearby hospital in March ２００X. Contrast-enhanced computer tomography scan showed contrast defect images in the pulmonary artery and lower extremity vein. She was diagnosed with pulmonary embolism and deep venous thrombosis and anticoagulant therapy was started. At the same time, a blood test revealed an abnormal increased platelet count（７４０，０００/μl）, and she was diagnosed as myeloproliferative disease（primary myelofibrosis, JAK２ mutation +）. We follow up with oral administration of a steroid because she had a low risk of primary myelofibrosis. However, the symptom had been lasting, she was admitted into our hospital for examining the origin of symptom and treatment. Cardiac echocardiography suggested the presence of pulmonary hypertension, and lung ventilation perfusion scintigraphy showed widespread wedge accumulation defect, depressed area in bilateral lungs, and ventilator blood flow mismatch. In cardiac catheterization, the mean pulmonary artery pressure was as high as ３７mmHg. Per the test results, she was diagnosed chronic thromboembolic pulmonary hypertension（CTEPH）secondary to primary myelofibrosis. We proposed invasive treatment（pulmonary artery endarterectomy, balloon pulmonary arterioplasty）, but she desired just oxygen administration and medication therapy.
It is reported that CTEPH develops in an organized thrombus after acute pulmonary embolism, but the mechanism of that development has not been revealed. In this case with primary myelofibrosis, we consider that the decrease of pulmonary vascular bed is due to a blood cell disorder and vascular remodeling is due to an increase of vascular endothelial growth factor and platelet derived growth factor secreted by abnormal increased platelet contributed to elevation of pulmonary artery pressure.