Nonprostatic diseases on PSMA PET imaging: a spectrum of benign and malignant findings

Abstract

PSMA PET imaging was originally used to assess biochemical recurrence of prostate cancer (PCa), but its clinical use was promptly extended to detection, staging and therapy response assessment. The expanding use of PSMA PET worldwide has also revealed PSMA ligand uptake in diverse nonprostatic diseases, which raised questions about the specificity of this imaging modality. Although not very common initially, a growing number of pathologies presenting PSMA uptake on PET have been reported in the last few years, and a proper interpretation of PSMA PET imaging findings suddenly became challenging and, to some extent, confusing. Compared to cytoplasmic PSMA expression in nonprostatic cells, the molecular features of apical PSMA expression in PCa cells can help to distinguish these various conditions. Correlations of imaging findings to patient history, to the expected pattern of disease spread and mainly to computed tomography (CT) and/or magnetic resonance imaging (MRI) characteristics will reinforce the distinction of lesions that are more likely related to PCa from those that could lead to an incorrect diagnosis. The overall benefits of endothelial PSMA expression, which is associated with the neovasculature of malignant neoplasms, will be highlighted, stating the potential use of PSMA ligand uptake as a theranostic tool. This review aims to cover the collection of nonprostatic diseases, including benign and malignant tumors, in a didactic approach according to disease etiology, with discussion of bone-related conditions and inflammatory and infectious processes.

Incidental finding of COVID-19 infection after [68Ga]Ga-PSMA-11 PET/CT imaging in a patient with prostate cancer

“…The patient was able to perform a serologic test only on April 25 which confirmed past COVID-19 infection: IgM negative and IgG positive. PSMA expression is not exclusive to prostate cells and it is described that benign processes such as inflammation or infection could have a variable, often mild, [ 68 Ga]Ga-PSMA uptake [5]. Nonetheless, different from what has been described with [ 18 F]FDG, the uptake of [ 68 Ga]Ga-PSMA-11 was low in our patient.…”

Meningioma uptake of 68Gallium-PSMA-11 as a pitfall on positron emission tomography/computer tomography

“…In conclusion, 68 Gallium-PSMA uptake is not entirely unique to prostate cancer and may be seen in a range of benign as well as malignant pathologies. 13 To this end, the knowledge of normal distribution of the tracer is paramount and acquiring collateral history is mandatory. It would be imperative to convey the benign nature of the findings to the requesting physician, as the images would be available externally to the multidisciplinary teams who may not be familiar with this modality.…”

Meeting report from the Prostate Cancer Foundation PSMA theranostics state of the science meeting

“…Separately, and because PSMA is expressed on the tumor neovasculature of many nonprostate solid tumors, applications outside of prostate cancer are also being explored. [24][25][26][27][28][29]…”