FDG-Avid But FAPI-Negative Intramucosal Carcinoma in a Colorectal Adenoma.
Shinobu Adaniya, Masao Murakami, Toshimitsu Momose
✦ AI-curated · Sources linked
Case in brief
A man in his 70s presented for follow-up of hepatocellular carcinoma, undergoing both FDG PET/CT and 18F FAPI-74 PET/CT. The FDG PET revealed intense focal uptake in the sigmoid colon, while the FAPI PET showed no abnormal uptake. Endoscopic resection confirmed carcinoma in adenoma confined to the lamina propria, indicating a lack of desmoplastic reaction.
What made this case unusual
The case highlights a significant discrepancy between FDG and FAPI PET findings, with FDG showing uptake in an early-stage carcinoma while FAPI did not, suggesting limitations of FAPI in detecting intramucosal lesions.
Diagnostic / clinical pearl
Clinicians should be aware that FAPI PET may not be reliable for detecting early intramucosal carcinomas, particularly in adenoma-dominant lesions.
Why it matters
Understanding the limitations of FAPI PET in early colorectal lesions is crucial for accurate diagnosis and management, especially in cases where FDG PET indicates potential malignancy.