Answer is B (Marked increase in the number of intraepethelial lymphocytes): The intraepethelial lymphocytes are usually, either decreased in number or normal. Marked increase in the number of intraepethelial lymhocytes is not seen and this is the single best answer of exclusion. The Hallmark of Whipple's disease is a small intestinal mucosa laden with macrophages. Accompanying changes include lymphatic dilatation suggesting lymphatic blockage. The lymphatic blockage is believed to be responsible for lipid deposition in the villi - Robbins Histopathological findings in Whipple's disease Characterisitc findings / Specific finding (Hallmark of disease) Small intestinal mucosa laden with foamy macrophages in the lamina propria, which are characteristically, Periodic -Acid - Schiff (PAS) positive. These PAS positive macrophages (monocytes) also contain gram positive - acid fast bacillus T whipleiiQ. (The substance in macrophages that stains positive with PAS is thought to be remnants of the cell wall of phagocytosed bacilli) Note : PAS positive macrophages are not pathognomic for Whipple's disease. They have also been isolated in other diseases eg. Mycobacterium Avail?, Intercellulare & Mycobacterium Tuberculosis. Associated findings Villi may be thickenned, widened or blunted Small intestinal mucosal and submucosal lymphatic vessels are dilated Lipid droplets / Lipid vacuoles / Lipid deposition may be seen The number of lamina propria plasma cells, lymphocytes and eosinophills are decreased (Samter's Immunologic Diseases by Austen and Samter 2nd /704) 'The number of intraepethelial lymphocytes is not increased' (Sternberg's Diagnostic Surgical Pathology 4th/1481) Disease that can be Diagnosed by Small-Intestinal Mucosal Biopsies Lesions Pathologic Findings Diffuse, specific * Whipple '.s disease Lamina propria contains macrophages containing PAS + material * .4gammaglobulinemia No plasma cells: either normal or absent villi ("flat mucosa") * Abetalipoproteinemia Normal villi; epithelial cells vacuolated with fat postprandially Patchy, specific * Intestinal lymphoma Malignant cells in lamina propria and submucosa * Intestinal lymphangiectasia Dilated lymphatics; clubbed villi * Eosinophilic gastroenteritis Eosinophil infiltration of lamina propria and mucosa * Amyloidosis Amyloid deposits * Crohn's disease Noncaseating granulomas * Infection by one or more microorganisms Specific organisms * Mastocvtosis Mast cell infiltration of lamina propria Diffuse, nonspecific * Celiac sprue Sho or absent villi; mononuclear infiltrate; epithelial cell damage; hyperophy of crypts * Tropical sprue Similar to celiac sprue * Bacterial overgrowth Patchy damage to villi; lymphocyte * Folate deficiency Sho villi; decreased mitosis in crypts; megalocytosis * Vitamin B12 deficiency Similar to folate deficiency * Radiation enteritis Similar to folate deficiency * Zollinger - Ellison syndrome Mucosal ulceration and erosion from acid * Protein -calorie malnutrition Villous atrophy; secondary bacterial overgrowth * Drug-induced enteritis Variable histology