Histology and immunohistochemistry. The left panel shows a microphotograph (magnification ×400, hematoxylin and eosin stain) showing smooth muscle in the wall of the cyst, indicated by a white bold arrow, and flattened endothelial-like cells lining the cyst wall, indicated by a bold black arrow. The right panel shows immunohistochemistry by marker D2-40 identifying the lymphatic endothelium, indicated by bold black arrows.