Chronic Diarrhea as the Presenting Feature of Amyloidosis with Multiple Myeloma: A Case Report Diagnosed by a Myocardial Biopsy.

A 73-year-old woman with a history of diarrhea for one year and other various symptoms was admitted to our hospital. Gastrointestinal endoscopy that included enteroscopy with multiple biopsies was performed. However, no significant findings were observed. Electrocardiography showed low voltage in all limb leads, and an echocardiogram showed thickened cardiac walls with granular sparkling pattern. A myocardial biopsy revealed amyloidosis, and a bone marrow biopsy showed multiple myeloma. This case suggests that we should suspect the possibility of amyloidosis in a patient with diarrhea and various symptoms involving multiple organ systems. Additionally, electrocardiograms and echocardiograms should be performed even when gastrointestinal biopsies reveal negative results.