Unusual Sole Extramedullary Diffuse Kidney Involvement in Multiple Myeloma Initial Workup Using 2-[ 18 F]FDG-PET/CT...

Area of Science:

• Oncology
• Nuclear Medicine
• Radiology

Background:

• Multiple myeloma (MM) commonly presents with bone marrow involvement.
• Extramedullary disease (EMD) in MM is often detected later in the disease course.
• 2-[18F]FDG-PET/CT is a valuable tool for staging and detecting MM EMD.

Purpose of the Study:

• To report an unusual case of sole diffuse kidney EMD in newly diagnosed MM.
• To illustrate the utility of 2-[18F]FDG-PET/CT in identifying atypical MM EMD patterns.
• To highlight the potential for diffuse organ involvement in MM.

Main Methods:

• A 63-year-old woman with newly diagnosed MM underwent 2-[18F]FDG-PET/CT.
• Imaging revealed significantly increased renal volume and intense, diffuse bilateral renal cortical uptake.
• Kidney biopsy confirmed extramedullary myeloma involvement.

Main Results:

• The 2-[18F]FDG-PET/CT scan identified diffuse kidney EMD as the only site of extramedullary disease.
• Renal involvement presented as increased kidney size and intense cortical FDG uptake.
• Urinary excretory cavities were not visualized, suggesting compromised renal function or infiltration.

Conclusions:

• This case demonstrates an uncommon presentation of MM with diffuse renal EMD.
• 2-[18F]FDG-PET/CT can detect atypical patterns of extramedullary myeloma, including diffuse organ infiltration.
• The findings emphasize the importance of considering diffuse organ involvement in MM diagnosis and staging.