The presence of effused chyle in the peritoneal cavity. Because of its extent, it is often defined as “chylous ascites” (see). In this case too, there may be very different causes, therefore, accurate clinical investigations also with imaging techniques are essential to design the most suitable medical-surgical therapy. The most common causes are: tumor infiltration of lymphatic structures – visceral lymph nodes – traumas (often of iatrogenic nature, for example during extensive lymphadenectomies in surgical therapy of renal cell cancer), or lymphangiodysplasias.