Uptake of the prostate-specific membrane antigen-targeted PET radiotracer 18F-DCFPyL in elastofibroma dorsi

Prostate specific membrane antigen (PSMA) avid nonprostatic benign and malignant disease: a pictorial review

Prostate specific membrane antigen (PSMA) positron emission tomography-computed tomography (PET-CT) is revolutionising the management of prostate cancer (PC) in primary staging and assessment of biochemical recurrence (BCR) through its higher diagnostic accuracy compared to both conventional imaging and previously available PET radiopharmaceuticals. PSMA is a transmembrane glycoprotein, highly expressed in prostate cancer, with its extracellular domain the target for PSMA PET radiopharmaceuticals. However, PSMA expression is not prostate specific and resultant PSMA uptake on PET-CT is not restricted to pathologies arising from the prostate gland. The increasing use of PSMA PET-CT has revealed PSMA uptake in a variety of non-prostatic benign and malignant diseases, which adds complexity to PET-CT interpretation and subsequent clinical management. This pictorial review will provide a thorough knowledge and understanding of the comprehensive range of PSMA avid non-prostatic benign and malignant diseases demonstrable on PSMA PET-CT, whilst highlighting the complimentary nature of other imaging modalities.

A Practical Guide to the Pearls and Pitfalls of PSMA PET Imaging

Prostate-specific membrane antigen (PSMA)-targeted PET agents have revolutionized the care of patients with prostate cancer, supplanting traditional methods of imaging prostate cancer, and improving the selection and delivery of therapies. This has led to a rapid expansion in both the number of PSMA PET scans performed and the imaging specialists required to interpret those scans. To aid those imagers and clinicians who are new to the interpretation of PSMA PET, this review provides an overview of the interpretation of PSMA PET/CT imaging and pearls for overcoming commonly encountered pitfalls. We discuss the physiologic distribution of the clinically available PSMA-targeted radiotracers, the commonly encountered patterns of prostate cancer spread, as well as the benign and malignant mimics of prostate cancer. Additionally, we review the standardized PSMA PET reporting systems and the role of PSMA in selecting appropriate patients for PSMA-targeted therapies.

Incidental Detection of Elastofibroma Dorsi With 68Ga-FAPI-46 and 18F-FDG PET/CT in a Patient With Esophageal Cancer

ABSTRACT

A 71-year-old man underwent 18F-FDG and 68Ga-FAPI-46 PET/CT for initial staging prior to surgery of a squamous cell carcinoma of the lower esophagus under the prospective study NCT04147494. Both scans showed increased uptake in the mid and distal esophagus without evidence of metastatic disease. A soft tissue right infrascapular mass with mild 18F-FDG and moderate 68Ga-FAPI-46 uptake was incidentally found. The patient underwent robotic-assisted Ivor-Lewis esophagectomy and excision of the right infrascapular mass. Histopathology of the right chest wall mass confirmed the diagnosis of elastofibroma.

Primary Peripheral Primitive Neuroectodermal Tumor of the Prostate on 18F-DCFPyL PET/CT

Peripheral primitive neuroectodermal tumor (PNET) is a group of malignant tumors composed of small round cells. Peripheral PNET usually originates in the skeletal system. However, the presence of PNET lesion in prostate is extremely rare. We report a case of a 40-year-old man who presented with dysuria for more than 2 months. Pelvic MRI indicated prostatic malignant tumor, and F-DCFPyL PET/CT showed an isolated prostatic mass with high uptake of F-DCFPyL. Although F-DCFPyL is very specific for prostatic adenocarcinoma, a final diagnosis of peripheral PNET was made by pathology examination.

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

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.