A previously healthy 47-year-old man presents with two weeks of progressive abdominal distension. Exam shows shifting dullness; paracentesis yields milky chylous fluid. What is the most likely underlying cause?

A previously healthy 47-year-old man presents with two weeks of progressive abdominal distension. Exam shows shifting dullness; paracentesis yields milky chylous fluid. What is the most likely underlying cause?

• A. Cirrhosis with portal hypertension
• B. Pancreatic cancer
• C. Lymphoma
• D. Tuberculosis peritonitis

Answer: (C)

Milky, triglyceride-rich ascitic fluid is chylous ascites, which results from leakage or obstruction of intestinal lymphatics. In adults, the most common malignant cause is lymphoma, where infiltration of retroperitoneal or mesenteric lymphatics disrupts lymph flow and lets chyle spill into the peritoneal cavity. This explains progressive abdominal distension with shifting dullness and a milky paracentesis sample. Other conditions can cause ascites, but they don’t typically produce milky chyle. Cirrhosis leads to nonchylous, straw-colored ascites due to portal hypertension. Pancreatic cancer and tuberculosis peritonitis can cause ascites but usually not milky chyle. Thus, lymphoma is the best explanation for the findings.

Milky, triglyceride-rich ascitic fluid is chylous ascites, which results from leakage or obstruction of intestinal lymphatics. In adults, the most common malignant cause is lymphoma, where infiltration of retroperitoneal or mesenteric lymphatics disrupts lymph flow and lets chyle spill into the peritoneal cavity. This explains progressive abdominal distension with shifting dullness and a milky paracentesis sample.

Other conditions can cause ascites, but they don’t typically produce milky chyle. Cirrhosis leads to nonchylous, straw-colored ascites due to portal hypertension. Pancreatic cancer and tuberculosis peritonitis can cause ascites but usually not milky chyle.

Thus, lymphoma is the best explanation for the findings.