FDG PET/CT in Sacroiliac IgG4 Disease

Area of Science:

• Immunology
• Radiology
• Pathology

Background:

• IgG4-related disease is a rare, fibroinflammatory condition that can affect virtually any organ.
• Diagnosis can be challenging due to its diverse clinical presentations and potential mimicry of other diseases.

Observation:

• A 68-year-old female presented with abdominal pain and elevated C-reactive protein.
• Abdominal CT revealed an irregular soft tissue mass anterior to the aorta, initially suspected to be neoplastic.
• 18F-FDG PET/CT demonstrated hypermetabolic activity in the abdominal mass and additional foci in the head and neck, sacroiliac joints, and pelvic floor muscles.

Findings:

• CT-guided biopsy of the sacroiliac joint confirmed IgG4-related disease.
• The imaging findings indicated a systemic inflammatory process consistent with IgG4-related disease.

Implications:

• This case highlights the importance of considering IgG4-related disease in the differential diagnosis of unexplained masses and systemic inflammation.
• Multimodality imaging, including 18F-FDG PET/CT, plays a crucial role in identifying affected sites and guiding biopsy.
• Early and accurate diagnosis of IgG4-related disease is essential for appropriate management and to prevent potential complications.