Picture Prognosis

A 47-year-old male presents with chronic diarrhea, abdominal distention, and muscle wasting. Lab results show macrocytic anemia, low albumin, and recurrent ascites managed with paracentesis. Small bowel endoscopy reveals erythematous and edematous mucosa. Biopsy confirms abundant PAS-positive macrophages in the lamina propria. What's your diagnosis?