Chylous Ascites: A Rare Initial Presentation of B-cell Lymphoma

Abstract

Chylous ascites (CA) is a rare form of ascites (1 in 20,000 cases) that results from the leakage of lipid-rich lymph into the peritoneal cavity. Almost two-thirds of all CA cases in developed countries are associated with malignancies including B cell lymphomas and cirrhosis, whereas infectious diseases including Tuberculosis account for the majority of cases in developing countries. In our case, CA was the initial manifestation of B cell lymphoma in an otherwise healthy male. A 65 year old male with past medical history of hypertension presented to the ED with gradually progressive abdominal distension along with early satiety for 6 weeks. He denied any fever, weight loss or night sweats. Physical exam revealed significant ascites. Initial blood work including CBC, BMP and liver function tests was normal. Serologies for hepatitis were negative and there was no evidence of cirrhosis on imaging. An ultrasound guided paracentesis was performed and approximately 6 L of grossly turbid and milk fluid was removed (Image 1).The ascitic fluid analysis showed a nucleated cell count of 2350cells/mm3 with a SAAG of 0.9, the triglyceride level was elevated at 250. Lights criteria were suggestive of an exudative effusion. Fluid cytology showed large neoplastic cells and very atypical nuclei. Immunohistochemistry (IHC) staining was positive for of CD20+ and BCL-2 suggestive of a non-Hodgkin's B-cell lymphoma (Image 2). FDG-PET/CT of the abdomen revealed significant FDG-avid disease with a heterogeneous necrotic mesenteric mass along with omental caking, ascites and mesenteric and retroperitoneal lymphadenopathy (Image 3). Patient was started on R-CHOP regimen along with a high protein and low fat diet. His symptoms subsequently improved and he is still undergoing treatment for his disease. B cell lymphomas can rarely present with CA.Despite its low incidence rate, CA is associated with a 40-70% mortality rate. The diagnosis of CA is based on the distinct characteristics of the ascitic fluid which include a milky appearance and a triglyceride level of >200 mg/dl. As seen in our case, fluid chemistry along with cytology and IHC staining can help distinguish malignancy from other etiologies of CA such as cirrhosis and infections. Advent of superior chemotherapy regimens has led to marked improvement in survival rates especially in patients with lymphomas. The treatment strategies need to be individualized as the outcome depends on the underlying etiology.Figure: Milky and cloudy fluid removed by paracentesis,characteristic of Chylous ascites.Figure: 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, 60x. (b)Wright-Giemsa with three neoplastic cells and very atypical nuclei, 100x. (c) Immunohistochemistry identification of CD20+ B-cells, 40x, (d) Large neoplastic cells are negative for the T-cell marker, CD3, 40xFigure: 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.