[Pulmonary artery intimal sarcoma: a clinicopathological analysis of three cases].

Objective: To investigate the clinicopathological characteristics, genetic features, diagnosis and differential diagnosis of pulmonary artery intimal sarcoma (PAIS). Methods: Three cases of PAIS were collected from Jiangsu Province People's Hospital (from February 2016 to November 2019). The clinical data, imaging examination, morphology, immunostaining, and molecular changes were retrospectively analyzed. Results: There were 1 male and 2 females (age: 32, 50, 60 years), who had symptoms of cough, asthma or chest tightness. Imaging findings indicated low density filling defects which were suspected as thrombus, embolism or myxoma. Grossly, the main tumor was located in the elastic arteries and their lobar branches, also extended into the atrium and ventricle, with lung parenchymal infiltration focally. Microscopically, tumor cells were predominantly composed of abundant spindle cells with obvious atypia and myxoid background, resembling fibroblastic or myofibroblastic differentiation. Active mitotic figures and necrosis could be seen in some areas. Immunohistochemical staining of vimentin was strongly positive, while pan-cytokeratin, S-100, desmin, Fli-1, CD31, SMA and ERG etc were variably positive only in focal areas. FISH detection showed amplification of MDM2 gene in three cases and EGFR gene in two cases. Metastatic lesions were found in one case by 18, 32 and 42 months after surgery respectively. There was no recurrence or metastasis in the other two cases. Conclusions: PAIS is one of exceptionally poor differentiated mesenchymal tumor that arises from the arterial intima of elastic pulmonary arteries. There was no definite differention in morphology. Gene detection shows amplification of MDM2 and EGFR gene. This tumor often has poor prognosis with aggressive behavior. Complete resection is the only effective therapeutic option. There is disagreement as to whether chemotherapy and radiotherapy can improve survival.