Unveiling a rare haemorrhagic malignant pleural effusion: The role of medical thoracoscopy in diagnosing primary pleural angiosarcoma

Abstract Primary pleural angiosarcoma (PPA) is a rare and challenging tumour to diagnose, often mistaken for other malignancies such as mesothelioma and lung cancer due to overlapping clinical and imaging features. We report a 52‐year‐old woman who presented with progressive shortness of breath and pleuritic chest pain. Imaging studies and thoracentesis revealed a large haemorrhagic left pleural effusion. Medical thoracoscopy (MT) showed a thickened and lobulated parietal pleura with multiple nodular lesions. Histopathological examination confirmed a diagnosis of angiosarcoma, characterized by pleomorphic tumour cells, a high Ki67 proliferation index and positive immunohistochemical markers, including CD31, D2‐40, Vimentin, and Factor VIII. Tragically, the patient developed a hospital‐acquired infection and passed away before any definitive treatment for the angiosarcoma could be initiated. This case underscores the diagnostic complexities of PPA and highlights the utility of MT in identifying this rare malignancy.