False positive lymph node activity on positron emission tomography (PET/CT) due to hemostatic compresses

Area of Science:

• Oncology
• Nuclear Medicine
• Surgical Pathology

Background:

• Combined positron emission tomography and computerized tomography (PET/CT) with 18-fluorodeoxyglucose (18-FDG) is a key imaging modality for staging various cancers, particularly for identifying lymph node involvement.
• Cancers of the uterine cervix commonly involve pelvic and para-aortic lymph nodes, making accurate staging crucial for treatment planning.

Observation:

• A patient with endometrial cancer underwent laparoscopic hysterectomy and cytoreductive surgery.
• Postoperative 18-FDG PET/CT revealed intense radiotracer uptake in the right common iliac lymph node chain.
• This finding prompted a surgical re-exploration to investigate the suspicious uptake.

Findings:

• The re-exploration identified no evidence of metastatic cancer in the right common iliac chain.
• The intense 18-FDG uptake was attributed to a granuloma, a benign inflammatory reaction.
• The granuloma was likely a response to a hemostatic sponge used during the initial surgery.

Implications:

• This case highlights a potential pitfall of 18-FDG PET/CT, where benign inflammatory processes can mimic malignant lymph node involvement.
• It underscores the importance of integrating imaging findings with clinical context and surgical findings for accurate diagnosis.
• While PET/CT is highly effective, false-positive results can occur, necessitating careful interpretation and sometimes further investigation.