ABSTRACT
Aim/Introduction: This is a case of [68 Ga]Ga-Prostate-specific membrane antigen(PSMA)-11 PET/CT in a 73-years old patient with significantly high iPSA level despite both multiparametric magnetic resonance imaging (mpMRI) and 12-core saturation biopsy negative for prostate cancer (Pca). Material(s) and Method(s): In November 2021 the patient underwent a routinary abdomen ultrasound with the detection of several pelvic and retro-peritoneal adenomegalies, confirmed by diagnostic CT. Initially the suspect of Pca origin was raised, due to high PSA levels (55 ng/dl versus 2.1ng/dl the previous year). A 12-samples saturation biopsy was then performed, with inconclusive result. Nevertheless, due to further increase in PSA level up to 77ng/dl in December (PSA doubling time approximately 4 months), a mpMRI was performed in January showing absence of clinically significant PCa (PIRADS 2) and persistence of enlarged pelvic lymph nodes. The patient was subsequently referred for a [68Ga]Ga-PSMA-PET/CT, which was performed and reported following standard EANM guidelines. A delayed 90 min scan on the pelvis was also acquired. Result(s): In accordance with previous mpMRI, PSMA-PET/CT detected no significant nor focal uptake within the prostate gland even at delayed acquisition (diffuse pattern, SUVmax 3.6). Interestingly, multiple PSMA-avid pelvic and retroperitoneal lymphadenopathies were detected (SUVmax 34) as well as a single, intense focal bone lesion at L3 vertebral body (SUVmax 14, corresponding with initial focal osteoblastic lesion at low-dose CT images-LDCT), and a single focal uptake in a left axillary lymph-node (SUVmax 19). Of note, the latter lymph-node was homolateral to the injection site of recent anti-SARS-Cov2 vaccination and without clearly pathological pattern on LDCT. However, due to its high PSMA expression, it was chosen for ultrasound-guided biopsy and finally diagnosed as Pca metastasis. Conclusion(s): Several malignancies can present with subdiaphragmatic nodal findings, but this is a highly interesting case as, despite the advanced metastatic spread at initial presentation, the primary Pca was detected by none of the diagnostic techniques. The importance of [68Ga]Ga-PSMA-PET/ CT was to rapidly pave the way to reach the final diagnosis by selecting the unusual axillary lesion with elevated PSMA expression as the target biopsy for a mini-invasive approach optimizing patient management;in addition, it was able to detect a single PSMA avid sclerotic lesion typical for initial bone spread of PCa.