Abstract
Hyperplastic mesothelial cells involving lymph node sinuses have only been recently described. Most nodal mesothelial cells are thought to originate from mesothelial surfaces disrupted by serosal effusions. Dislodged mesothelial cells likely gain access to submesothelial lymphatics via mesothelial stomata and disseminate to draining lymph nodes. Unusual lymph node architectural patterns result when benign sinus mesothelial cells occur concurrently with a neoplastic nodal process. We describe a young man who developed diffuse metastases from a primary cardiac angiosarcoma. His periaortic lymph nodes contained metastatic angiosarcoma and hyperplastic mesothelial cells with a sinus distribution. The patient had a clinical history of progressive haemoperitoneum, exacerbated by thrombocytopaenia and disseminated intravascular coagulation. Massive haemoperitoneum of 5000 ml was confirmed at autopsy. This is the first report to suggest that multiple episodes of intraperitoneal haemorrhage and ascites may both act in the same manner to cause dislodgment and dissemination of mesothelial cells to draining lymph node sinuses.