68Ga-PSMA Uptake in Anal Fistula on PET/CT Scan

Area of Science:

• Nuclear medicine
• Oncology
• Radiology

Background:

• Prostate-specific membrane antigen (PSMA) PET/CT is a key imaging modality for prostate cancer staging.
• PSMA expression is typically associated with prostate cancer cells.
• Recent studies indicate PSMA can be upregulated in certain benign inflammatory conditions.

Observation:

• A patient with high-risk prostate cancer undergoing primary staging with Gallium-68 (Ga)-PSMA PET/CT presented with unexpected increased Ga-PSMA uptake.
• The increased uptake was localized to a known anal fistula in the perianal region.
• The patient had a history of complex perianal fistulas with ongoing inflammation and infection.

Findings:

• This case illustrates increased Ga-PSMA uptake in a benign inflammatory condition (anal fistula).
• The findings align with emerging evidence of non-specific Ga-PSMA uptake in various inflammatory processes.
• This highlights a potential pitfall in interpreting Ga-PSMA PET/CT scans.

Implications:

• Increased Ga-PSMA uptake in benign conditions like anal fistulas can mimic metastatic disease.
• Radiologists and nuclear medicine physicians must be aware of this potential false positive.
• Careful correlation with patient history and other imaging findings is crucial for accurate diagnosis.