Chylous Ascites: A Review of Pathogenesis, Diagnosis and Treatment

Abstract

Chylous ascites (CA) is a rare form of ascites that results from the leakage of lipid-rich lymph into the peritoneal cavity. This usually occurs due to trauma and rupture of the lymphatics or increased peritoneal lymphatic pressure secondary to obstruction. The underlying etiologies for CA have been classified as traumatic, congenital, infectious, neoplastic, postoperative, cirrhotic or cardiogenic. Since malignancy and cirrhosis account for about two-thirds of all the cases of CA in Western countries, in this article we have attempted to reclassify CA based on portal and non-portal etiologies. The diagnosis of CA is based on the distinct characteristic of the ascitic fluid which includes a milky appearance and a triglyceride level of >200 mg/dL. The management consists of identifying and treating the underlying disease process, dietary modification, and diuretics. Some studies have also supported the use of agents such as orlistat, somatostatin, octreotide and etilefrine. Paracentesis and surgical interventions in the form of transjugular intrahepatic portosystemic shunt (commonly known as TIPS), peritoneal shunt, angiography with embolization of a leaking vessel, and laparotomy remain as treatment options for cases refractory to medical management.

Keywords: Ascitic fluid; Chylous ascites; Cirrhosis; Lymphatic system; Portal hypertension.

Fig. 1.. A schematic representation depicting the lymphatic drainage with the major lymphatic channels in the thoraco-abdominal region.

Fig. 2.. Etiological classification along with differential diagnosis of various causes of portal hypertension based on the site of resistance to the portal blood flow (portal and non-portal hypertensive causes).

Fig. 3.. Gross and histological findings.

(a) Endoscopic image showing dilated duodenal villi in a patient with intestinal lymphangiectasia. (b) Tissue biopsy with hematoxylin and eosin stain, showing dilated lacteals (arrow) at 10x magnification. (c) Biopsy at 40x magnification.

Fig. 4.. Typical sample of chylous ascites, showing milky and cloudy fluid.

Fig. 5.. Ascitic fluid cytology from a patient with chylous ascites.

(a) Thin prep cytospin preparation showing a moderately cellular specimen with large cells and prominent nucleoli surrounded by benign small lymphocytes, at 60x magnification. (b)Wright-Giemsa staining with three neoplastic cells and very atypical nuclei, at 100x magnification. (c) Immunohistochemistry identification of CD20+ B-cells, at 40x magnification. (d) Large neoplastic cells showing negativity for the T-cell marker CD3, at 40x magnification.

Fig. 6.. Axial and coronal CT (upper panels) and fused FDG-PET/CT (lower panels) of a patient with new onset chylous ascites with fluid cytology consistent with B cell non-Hodgkin lymphoma.

Images show significant FDG-avid disease in the abdomen, including a heterogeneous necrotic mesenteric mass (white arrows), omental caking (black arrows), ascites (black arrowheads) and mesenteric and retroperitoneal lymphadenopathy.

Fig. 7.. Algorithm for the management of chylous ascites.