Whipple's disease with normal duodenal histology diagnosed by ileal biopsy using balloon endoscopy.

A 34 year-old previously healthy Japanese woman presented with a 4 year history of migratory arthralgia, chronic diarrhea, mild fever, and 10 kg weight loss. She was initially misdiagnosed with seronegative arthritis, followed by eosinophilic gastroenteritis. Oral prednisolone was found to be ineffective.