History: The patient was a 45 year-old man with weight loss, worsening joint pains, fever, and night time sweats. Blood culture, urine culture, and PPD test were negative. An abdominal x-ray showed non-specific mesenteric lymphadenopathy. A biopsy of the upper gastrointestinal tract was performed. The current biopsy was obtained from the duodenum.

Histologic Highlights of this Case:

• The lamina propria is filled by foamy histiocytes which expands and blunt the villi (area 1). Note that the foamy histiocytes are not accompanied by significant acute or chronic inflammation.

• Brunner's gland are present in this specimen and helps to identify it as duodenum (area 2).

• The foamy histiocytes are strongly positive for periodic acid Schiff (PAS) stain and they are diastase resistant. No acid fast bacilly or fungal organisms are demonstrated by acid fast stain or Gomori's methanamine silver (GMS) stain.

Hematoxylin & eosin

Hematoxylin & eosin

• Whipple disease typically affect middle-aged men with malabsorption as the gastrointestinal manifestations. Patients often have rthritis, chronic weight loss, lymphoadenopathy, and neuropsychiatric manifestations.
• The small intestine is most frequently affected but esophagus, stomach, and colon can also be involved.
• Endoscopically, mucosal folds are thickened and with yellow-white plaques which reflects the histologic changes of foamy histiocytes (yellow-white in color), thickening of villi and expanded lamina propria (thickened mucosa fold). Involvement may be diffuse or patchy.
•  Whipple disease is rresulted from an actinobacterium, Tropheryma whippelii, which is cultivation-resistant. These organisms are strongly positive for periodic acid Schiff (PAS) and they are diastase resistant. The foamy histiocytes are fully filled by these bacteria. Their presence can also be demonstrated by electron microscopy and polymerase chain reaction (PCR).

Hematoxylin & eosin

PAS

PAS with diastase