Isolated Testicular Metastasis from Prostate Cancer Detected on Ga-68 PSMA PET/CT Scan

Abstract

Although prostate cancer can metastasize to any part of the body, isolated testicular metastasis is very rare and only few cases have been reported so far. Here we present a case of 65-year-old male patient, known case of prostate adenocarcinoma, referred for ⁶⁸Ga-PSMA PET/CT scan, post radiotherapy, and androgen deprivation therapy, for rising serum PSA levels. He was found to have an isolated testicular metastasis on the scan. This report highlights the importance of ⁶⁸Ga-PSMA PET-CT scan in detecting these unusual and rare sites of metastasis from prostate cancer.

Fig. 1.

A 65-year-old male patient, known case of adenocarcinoma prostate gland (Gleason’s score 7 (4 + 3)), diagnosed 3 years ago, post radiotherapy and androgen deprivation therapy, presented with rising serum PSA levels, with a recent value of 7.07 ng/ml was referred for ⁶⁸Ga-PSMA PET/CT scan. Maximal intensity projection (MIP) of ⁶⁸Ga-PSMA PET/CT scan (a) and axial PET, CT, and fused PET/CT images (b–d) showed mild inhomogeneous PSMA uptake in the prostate gland. Axial and Sagittal PET, CT, and fused PET/CT images (e–j) revealed PSMA avid ill-defined heterogeneously enhancing lesions in the right testis likely metastatic. Later, the patient underwent bilateral orchiectomy, and histopathologic report confirmed metastatic prostatic adenocarcinoma to the right testis. Prostate-specific membrane antigen is a transmembrane protein, which is overexpressed in prostate carcinoma cells [1]. ⁶⁸Ga-PSMA ligand PET/CT is a highly sensitive and specific imaging technique for the detection of primary and metastatic prostate cancer [2]. Metastatic prostate cancer lesions are commonly found in lymph nodes, bones, and lungs but infrequently seen in testes [3]. Several pathophysiological mechanisms have been described to explain metastatic spread to the testes, like retrograde venous extension, retrograde lymphatic spread, or direct extension through the vas deferens. Usually, testicular metastases in prostate cancer are suggestive of advanced prostate disease. Very rarely, the testis may be the isolated site of metastatic spread, as seen in our case. To the best of our knowledge, very few case reports have been published about solitary testicular metastasis detected by ⁶⁸Ga-PSMA PET/CT scan [4–7]. However, in literature, there are few articles that describe ⁶⁸Ga-PSMA uptake in non-prostatic conditions [8–10]. Metastatic disease to testicles from solid tumors is very rare; a study of 738 patients with solid malignant neoplasms found metastasis to testicles in 0.68% of patients [11]. Approximately 4% of testicular metastases are found incidentally during orchiectomy for advanced prostate cancer [12]. This report highlights the rare finding of testicular metastasis from prostate cancer and the potential of ⁶⁸Ga-PSMA-targeted PET/CT scan for detection of metastases even in these atypical sites

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The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patient understands that their names and initials will not be published, and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflict of Interest

Dr. Nitin Gupta, Dr. Sudip Dey, Dr. Ritu Verma, and Dr. Ethel S.Belho declare that they have no conflicts of interest. There is no source of funding.