Introduction
Prostate cancer is the most common cancer in men, detected through elevated prostate-specific antigen (PSA) levels and confirmed by imaging and biopsy [ 1 ]. The staging and management of prostate cancer have been significantly improved by advanced imaging techniques such as magnetic resonance imaging (MRI) and prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT). PSMA PET/CT offers high sensitivity and specificity for detecting both primary and metastatic disease [ 2 ]. However, it may yield atypical results, complicating the diagnostic process [ 3 ]. This case report highlights a 62-year-old male with prostate cancer whose rising PSA levels and PSMA PET/CT indicated potential splenic metastasis. Subsequent MRI suggested a benign hemangioma, underscoring the importance of thorough diagnostic evaluations in prostate cancer staging.
Case presentation
A 62-year-old male presented with progressively increasing PSA levels since July 2021 (Figure 1 ). He denied any history of prostatitis, prostate manipulation, or urinary tract infections. He had been on testosterone replacement therapy with pellets for testicular hypogonadism.
He underwent an extensive diagnostic workup. The 4Kscore is a blood test that measures four kallikrein protein levels (total PSA, free PSA, intact PSA, and human kallikrein 2) to assess the risk of aggressive prostate cancer [ 4 ]. In this case, the results of the 4Kscore test indicated a 21% probability of aggressive prostate cancer. The Prostate Imaging Reporting and Data System (PI-RADS) is a standardized reporting system for evaluating the prostate for cancer [ 5 ]. The MRI showed a PI-RADS 5 lesion in the left posterior lateral peripheral zone at the mid-gland (Figure 2 ).
The patient underwent cystoscopy, urethral dilation, and MRI fusion prostate biopsies. The pathology results were as follows: (1) left lateral base: adenocarcinoma, Gleason score 7, grade group 3 (40% involvement, area of interest 70%); (2) left lateral mid: adenocarcinoma, Gleason score 6, grade group 1 (80% involvement); and (3) left mid: adenocarcinoma, Gleason score 6, grade group 1 (25% involvement); left base: adenocarcinoma, Gleason score 6, grade group 1 (20% involvement). Eight additional cores showed benign prostate tissue.
PSMA PET/CT scan demonstrated abnormal tracer activity in the posterior prostatic peripheral zone at the mid-gland and prostatic base, with the highest uptake intensity noted at the left posterolateral prostatic mid-gland peripheral zone. Additionally, there was focal intense tracer activity in the spleen consistent with metastatic prostate cancer based on tracer avidity and specificity for PSMA expression on prostate cancer cells (Figures 3 , 4 ).
To further evaluate the suspicious splenic lesion identified on the PSMA PET/CT, an MRI of the abdomen was performed. The MRI findings indicated that the splenic lesion exhibited imaging characteristics consistent with a hemangioma rather than metastatic disease (Figure 5 ). Additionally, lumbar spine hemangiomas were noted.
Discussion
This case underscores the complexity of diagnosing and staging prostate cancer, particularly with atypical imaging findings. The patient’s rising PSA levels and subsequent biopsy confirmed the presence of prostate adenocarcinoma, Gleason score 7. The unexpected PSMA PET/CT findings of focal uptake in the spleen initially suggested possible metastasis, which was later clarified as a benign hemangioma through comprehensive abdominal MRI. Splenic hemangiomas are the most common benign spleen tumors [ 6 ].
The patient’s history of hypogonadism and use of testosterone replacement therapy were noted but did not appear to influence the imaging findings. It is important to note that a team-based approach with urologists, radiation oncologists, radiologists, medical oncologists, and pathologists, along with multiple imaging modalities including PSMA PET/CT and MRI, and biopsy plus laboratory data, are required to make a proper diagnosis and stage prostate cancer.
Published case reports show PSMA uptake in inflammatory and infectious diseases such as neurocysticercosis, tuberculosis, sarcoidosis, osteomyelitis, and nodular fasciitis; benign tumors such as meningioma, schwannoma, neurofibromas, thyroid and parathyroid adenomas, angiolipoma, hemangiomas, thymomas, pseudoangiomatous stromal hyperplasia of the breast, adrenal adenoma, pancreatic serous cystadenoma, intramuscular myxoma, desmoid tumor, and acrochordon; and malignant tumors such as gliomas, thyroid cancer, breast cancer, lung cancer, hepatocellular cancer, pancreatic cancer, neuroendocrine cancer, gastric adenocarcinoma, endometrium cancer, Ewing sarcoma, osteosarcoma, and multiple myeloma, among many others [ 7 ].
Important to note is an Australian study by Dr. Hofman and his team published in The Lancet , which showed PSMA PET/CT technique had 92% accuracy at detecting metastases versus 65% accuracy with traditional CT and bone scans [ 8 ]. Furthermore, the radiation exposure from PSMA PET/CT was substantially lower than from CT and bone scans [ 8 ]. Clearly, PSMA PET/CT is a powerful and valuable imaging tool. However, it can show malignant and benign conditions.
Conclusions
PSMA PET/CT is a valuable tool in the staging of prostate cancer as it has sensitivity and specificity for detecting both primary and metastatic disease. However, this case highlights the need for a multidisciplinary approach, as well as comprehensive testing, including further imaging such as MRI and PSA level, to confirm the staging of prostate cancer. The PSMA avidity in the spleen initially thought to be metastasis was later identified to be a hemangioma via MRI. This misdiagnosis was avoided through comprehensive testing, which integrated multiple imaging techniques, along with blood tests and clinical pictures. It is important to note benign reasons for PSMA avidity while utilizing PSMA PET to stage prostate cancer.
We are grateful to Dr. Ali Borhan and the team at Honor Health Scottsdale Shea Medical Center for their invaluable assistance in this patient’s diagnostic workup.
Disclosures
Human subjects: Consent was obtained or waived by all participants in this study.
Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following:
Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work.
Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work.
Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.
Author Contributions
Concept and design: Hemanthkumar Athiraman
Acquisition, analysis, or interpretation of data: Hemanthkumar Athiraman, Yerko Borghero, Jessica Guido, Katherine Miller
Drafting of the manuscript: Hemanthkumar Athiraman
Critical review of the manuscript for important intellectual content: Hemanthkumar Athiraman, Yerko Borghero, Jessica Guido, Katherine Miller
Supervision: Hemanthkumar Athiraman, Yerko Borghero
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