Carcinoma of Unknown Original Identified as Renal Cell Carcinoma by 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Scan: A Report of Two Cases

Yumiko Kono; Keita Utsunomiya; Chisato Ohe; Nae Takizawa; Noboru Tanigawa

doi:10.7759/cureus.29827

Carcinoma of Unknown Original Identified as Renal Cell Carcinoma by 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Scan: A Report of Two Cases

Cureus. 2022 Oct 2;14(10):e29827. doi: 10.7759/cureus.29827. eCollection 2022 Oct.

Authors

Yumiko Kono¹, Keita Utsunomiya¹, Chisato Ohe², Nae Takizawa³, Noboru Tanigawa¹

Affiliations

¹ Department of Radiology, Kansai Medical University, Osaka, JPN.
² Department of Pathology and Laboratory Medicine, Kansai Medical University, Osaka, JPN.
³ Department of Urology and Andrology, Kansai Medical University, Osaka, JPN.

Abstract

Imaging is useful in identifying the primary site of an unknown primary cancer, and ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is an excellent imaging modality for identifying the primary lesion. However, a potential limitation is that ¹⁸F-FDG is physiologically excreted from the kidneys, thus masking renal lesions. In this report, we describe two cases of cancer of unknown origin that were detected as originating from renal cancer on ¹⁸F-FDG PET/CT. Both cases showed abnormal nodular accumulation of ¹⁸F-FDG in the kidney, which can be distinguished from the physiological excretion of ¹⁸F-FDG in the urinary tract. It is clinically crucial to be able to confirm the possibility of renal cancer, and careful observation of the urinary tract with ¹⁸F-FDG PET/CT can be useful.

Keywords: 18f-fluorodeoxyglucose positron emission tomography (18f-fdg pet); carcinoma of unknown origin; renal cell carcinoma; renal cell metastasis; tumor imaging.

Publication types

Case Reports