PAIS grows within the lumen of pulmonary arteries and eventually occludes those vessels. Common symptoms of primary pulmonary arterial sarcoma include dyspnea, chest pain, edema, cough, and hemoptysis [4, 5], it mimics pulmonary embolism (PE), which is characterized by pulmonary artery luminal narrowing or occlusion in computer tomography (CT) . How to diagnose the tumor originated from pulmonary artery accurately is great challenge in the clinical, because of insidious onset and symptoms indistinguishable from pulmonary thromboembolic diseases.
This rare case had relapse of chest oppression because of pulmonary artery intimal sarcoma, who was previously diagnosed as solitary fibrous tumor after the first surgery. Echocardiography reflected blood stream, calcification and blood velocity, which was useful for the detection of PAIS. 18F-FDG image showed multiple hyper-metabolic lesions consistent with lytic bone changes after the second surgery. Several case reports validated 18F-FDG PET/CT had some merits in the diagnosis of mesenchymal derived sarcomas,18F-FDG uptake in the higher-grade sarcoma correlated with mitotic count and grade [5,6,7,8]. The second post-operative pathology showed much more atypia and heterogeneity, significantly higher expression of CD34, which is hallmark of neo-vasculature, the proliferation index of Ki-67 increased as well.
This is the first report of longitudinal observation of SFT development into a PAIS with multiple bone metastases. Till now, the mechanism of tumor initiation, development and metastasis is not fully elucidated, the biological behavior is not fully identified, which is really great challenge in the oncology. Nuclear medicine and molecular imaging can describe tumor metabolism, receptor expression and angiogenesis, which serves as valuable surrogates of metastasis and prognosis. Integrin αvβ3 overexpressed on activated endothelial cells, and medicated tumor growth, local invasiveness and metastatic potential. In this case, if antitumor treatment was given after second operation, maybe the multiple metastasis can be avoided, which has been observed in the well differentiated neuroendocrine tumor. If patient was examined on time with 99mTc-Galacto-RGD2 SPECT/CT and 18F-FDG PET/CT, metastatic lesions would be found earlier than morphological changes. 99mTc-Galacto-RGD2 SPECT/CT was critical in the diagnosis of SFT, and further revealed metastatic potential and angiogenesis which led to development and metastasis. Therefore, we recommend that patient undergoes systemic evaluation of preoperative 99mTc-Galacto-RGD2 SPECT/CT, and necessary nuclear medicine and molecular imaging after surgery to early detect the metastasis. However, whether to perform systematic treatment, it is worthy of further discussion. This longitudinal observation of SFT development and progression to malignant pulmonary artery intimal sarcoma, which sheds light on tumor development and metastasis.