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Case Report
False-positive findings on 18-Fluoro-deoxy-glucose positron emission tomography due to granulomatous inflammation in a rectal cancer patient with an extensive tattoo
1 Department of Visceral, Transplant and Thoracic Surgery, Center of Operative Medicine, Medical University of Innsbruck, Innsbruck, Austria
2 Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria
Address correspondence to:
Reinhold Kafka-Ritsch
Department of Visceral, Transplant and Thoracic Surgery, Center of Operative Medicine, Medical University of Innsbruck, Anichstraße 35, 6020 Innsbruck,
Austria
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Article ID: 100102Z12KE2022
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Esswein K, Gassner E, Bale R, Kafka-Ritsch R. False-positive findings on 18-Fluoro-deoxy-glucose positron emission tomography due to granulomatous inflammation in a rectal cancer patient with an extensive tattoo. J Case Rep Images Surg 2022;8(1):16–21.ABSTRACT
Introduction: In patients with colorectal cancer a combined 18-Fluoro-deoxy-glucose positron emission tomography with computed tomography (CT) may be useful in advanced or recurrent disease to assess distant metastases. In the interpretation several pitfalls must be considered.
Case Report: A 37-year-old woman presented with metachronous liver metastases three years after the first diagnosis of rectal cancer. A second-line chemotherapy and stereotactic radiofrequency ablation was performed. Six months after the intervention, the follow-up magnetic resonance imaging revealed new liver lesions with indefinite diffusion impairment and pathologic contrast enhancement in portal venous and hepatobiliary phase. Further investigation with combined 18-Fluoro-deoxy-glucose positron emission tomography with CT showed for malignancy suspicious glucose-uptake in the respective liver lesions and additional in unilateral enlarged inguinal lymph nodes. Because of the uncommon findings, histologic specimen was obtained. Histology revealed no malignancy, but granulomatous hepatitis and lymphadenitis consistent with sarcoid-like reaction. Furthermore, deposition of tattoo pigment was found in the enlarged lymph nodes, most likely deriving from a large tattoo located on the right lower extremity.
Conclusion: We describe a case of a rectal cancer patient with misleading imaging findings on combined 18-Fluoro-deoxy-glucose positron emission tomography with CT. Awareness of rare conditions such as granulomatous inflammation and false-positive findings is key in the presence of uncommon findings, like in this case, suggested spread outside the metastatic pathway.
Keywords: Colorectal liver metastases, Magnetic resonance imaging, Sarcoid-like reaction, Sarcoidosis, Stereotactic radiofrequency ablation
SUPPORTING INFORMATION
Author Contributions
Katharina Esswein - Substantial contributions to conception and design, Acquisition of data, Analysis of data, Interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Eva Gassner - Substantial contributions to conception and design, Acquisition of data, Analysis of data, Interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Reto Bale - Substantial contributions to conception and design, Acquisition of data, Analysis of data, Interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Reinhold Kafka-Ritsch - Substantial contributions to conception and design, Acquisition of data, Analysis of data, Interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Guarantor of SubmissionThe corresponding author is the guarantor of submission.
Source of SupportNone
Consent StatementWritten informed consent was obtained from the patient for publication of this article.
Data AvailabilityAll relevant data are within the paper and its Supporting Information files.
Conflict of InterestAuthors declare no conflict of interest.
Copyright© 2022 Katharina Esswein et al. This article is distributed under the terms of Creative Commons Attribution License which permits unrestricted use, distribution and reproduction in any medium provided the original author(s) and original publisher are properly credited. Please see the copyright policy on the journal website for more information.
