Intestinal Lymphangiectasia Protein-Losing Enteropathy

A 22-year-old woman presents with a 6-year history of progressive peripheral edema, ascites, and chylous pleural effusions. She has chronic mild diarrhea and recurrent respiratory infections. On examination, she has pitting pedal edema, distended flanks with shifting dullness, and dilated superficial lymphatics on the medial thigh. Laboratory investigations reveal marked hypoalbuminemia (1.8 g/dL), hypogammaglobulinemia with reduced immunoglobulins, and profound lymphopenia (600/µL). Fecal alpha-1 antitrypsin clearance is markedly elevated, confirming protein-losing enteropathy. Upper GI endoscopy of the duodenum reveals the appearance marked as **A** in the diagram. Which of the following best describes the pathophysiology underlying this endoscopic finding?