类风湿关节炎滑膜炎。淋巴细胞与浆细胞浸润的慢性炎症使增生性结节下方呈现为蓝色区域。滑膜增厚，形成许多绒毛样突起，即血管翳，血管翳具有破坏性，可侵蚀关节软骨，最终破坏关节。
类风湿关节炎：手畸形 肘结节(肉眼) 结节(低倍镜) 滑膜炎血管翳(低倍镜)
This is the synovium in rheumatoid arthritis. There is chronic inflammation with lymphocytes and plasma cells that produce the blue areas beneath the nodular proliferations. This "pannus" is destructive and produces erosion of the articular cartilage, eventually destroying the joint.