Primary pleural angiosarcoma as a mimicker of mesothelioma: a case report **VS**.

Primary pleural angiosarcoma is a rare and clinically aggressive tumor. Patients usually present with chest pain, dyspnea, hemoptysis and/or cough. Radiologic studies reveal diffuse pleural thickening and pleural effusion with or without mass lesion. The clinical and radiological features both resemble those of mesothelioma, and its definite diagnosis requires careful histologic examination. However, frequent epithelioid feature and immunoreactivity to cytokeratin in primary pleural angiosarcoma further complicate the pathologic diagnosis. The use of proper immunohistochemical stains is often needed to support endothelial differentiation in the tumor cells and to exclude metastatic carcinoma and mesothelioma. We report the case of a 49-year-old male patient with primary pleural angiosarcoma, who presented with initial hemothorax, followed by a rapid progress to an inoperable status.