Related Experiment Video
Updated: May 20, 2026
Analysis of 18FDG PET/CT Imaging as a Tool for Studying Mycobacterium tuberculosis Infection and Treatment in Non-human Primates
Published on: September 5, 2017
FDG-PET-positive foreign-body granuloma mimicking residual germinal tumor infiltration
Zdeněk Rehák1, Petr Szturz, Eva Krejčí
1Department of Nuclear Medicine, PET centre, Masaryk Memorial Cancer Institute, Brno, Czech Republic.
Abstract:
In some patients, granulomatous reactions around foreign-bodies with FDG-PET positivity may be misinterpreted as malignancy. We report a case of a 31-year-old man diagnosed with testicular germinal tumor with retroperitoneal and left supraclavicular metastases. The diagnosis was based on left supraclavicular lymph node biopsy. Restaging examinations after orchiectomy and chemotherapy showed normalization of tumor markers and significant regression of the retroperitoneal infiltrate, however, with a residual FDG-PET positive lesion in the left supraclavicular fossa. The etiology behind this infiltration was revealed by a repeated histological examination, which surprisingly showed a foreign-body granuloma formation around a cotton pad left after the first surgery.
Insights
Foreign-body granulomas can mimic malignancy on FDG-PET scans, leading to misdiagnosis. A case highlights how a retained surgical cotton pad caused a false positive, emphasizing the need for thorough patient history.
Area of Science:
- Oncology
- Nuclear Medicine
- Pathology
Background:
- Granulomatous reactions to foreign bodies can present with fluorodeoxyglucose-positron emission tomography (FDG-PET) avidity.
- Such findings can be mistaken for malignant lesions, complicating patient management.
Observation:
- A 31-year-old man with testicular germinal tumor and metastases showed a persistent FDG-PET positive lesion after treatment.
- Initial diagnosis of metastasis was based on lymph node biopsy.
- Despite tumor marker normalization and infiltrate regression, the lesion remained.
Findings:
- Repeated histological examination revealed a foreign-body granuloma around a retained cotton surgical pad.
- The granuloma mimicked malignancy on FDG-PET imaging.
Implications:
- This case underscores the importance of considering foreign-body reactions in the differential diagnosis of FDG-PET positive lesions.
- Careful review of surgical history and potentially repeat biopsies are crucial to avoid misinterpreting benign inflammatory processes as recurrent or residual malignancy.
