Secondary Gastrointestinal Amyloidosis With Increased 18 F-FDG Uptake as the Only Presentation in a Patient With Multiple Myeloma.

A 63-year-old woman presented with abdominal pain and hematochezia was referred for 18 F-FDG PET/CT for the underlying malignancy. PET/CT detected diffuse thickening of the bowel walls with intense radioactivity in the colons. She was later diagnosed with multiple myeloma and secondary gastrointestinal amyloidosis, and achieved complete response of myeloma and amyloidosis after 9 cycles of chemotherapy. This case highlighted that gastrointestinal abnormality caused by amyloidosis might be the only presenting symptoms and findings in 18 F-FDG PET/CT in patients with multiple myeloma.