Triple Primary Malignancy Detection in an Elderly Male: A Case Report on Concurrent Prostate Cancer, Clear Cell Renal Cell Carcinoma, and Metastatic Melanoma Identified by PSMA PET-CT

Abstract

We report the management of a 76-year-old male presenting with primary metastatic melanoma, prostatic carcinoma, and clear cell renal cell carcinoma. Each of the three cancers was identified via PSMA PET-CT, thought to be unique to prostate cancer identification. Management of this patient included axillary lymph node resection, radiation therapy, radical nephrectomy, and immunotherapy. This case emphasizes the need for a multimodal approach and a broad differential diagnosis when managing cancer patients. Furthermore, the full potential of PSMA PET-CT has yet to be established.

1. Introduction

This case study reports the presentation of three distinct primary malignancies in a 76-year-old male patient with Prostate-Specific Membrane Antigen (PSMA) Positron Emission Tomography (PET). The simultaneous presence of renal cell carcinoma, melanoma, and prostate cancer is highly uncommon. However, the identification of non-prostatic malignancies with PSMA PET-CT is becoming increasingly documented in the literature.1, 2, 3, 4, 5

The role of the PSMA PET-CT in this case highlights its recent increasing relevance in the fields of urology and oncology.^6,7 PSMA is a transmembrane carboxypeptidase expressed in prostate cancer cells and has been deemed a reliable target for both diagnostic and therapeutic therapies for prostate cancer. The finding of non-prostatic malignancies, as seen in this case, adds to the growing body of evidence supporting the versatility of PSMA PET-CT in detecting various cancers and its potential as a broader diagnostic tool. Ozcan et al. conducted a thorough investigation of incidentally detected malignancies other than prostate cancer with gallium-68 PSMA PET-CT, demonstrating the previously unknown versatility of this diagnostic imaging modality.⁸

This report aims to discuss the diagnostic journey of this patient, the role of PSMA PET-CT in identifying multiple malignancies, the potential similarities or connections between these cancers, and highlight the therapeutic approaches undertaken in this complex urological presentation.

2. Case Presentation

We report the management of a 76-year-old male suffering from three primary malignancies: clear cell renal cell carcinoma, prostatic carcinoma, and metastatic melanoma. The patient initially presented with a grossly enlarged prostate and an elevated prostate-specific antigen (PSA) level of 7.3ng/mL. Subsequent prostate MRI identified a PIRADS 5 lesion and a 217cc prostate. Prostate needle biopsy confirmed the diagnosis of Gleason score 3 + 4 = 7 prostate cancer.

In addition to the prostate cancer (Fig. 1), a subsequent PSMA PET-CT unexpectedly revealed a right 11cm infiltrative and heterogenous kidney mass (Fig. 2), a right proximal 24mm sclerotic femur lesion (Fig. 2), and an enlarged left axillary lymph node (Fig. 3). The lymph node measured 35mm on the short axis with an SUV max of 4.1. Biopsy of the enlarged lymph node revealed metastatic melanoma for which the patient was started on pembrolizumab. Biopsy of the right renal mass was histologically consistent with clear cell renal cell carcinoma.

Fig. 1.

PSMA PET-CT – Axial View Prostate Cancer

Axial view PSMA PET-CT demonstrating focal intense radiotracer uptake within the prostate.

Fig. 2.

PSMA PET-CT – Coronal View Kidney Mass and Femur Lesion

Coronal view PSMA PET-CT demonstrating an 11cm heterogenous mass in the right kidney with intense radiotracer uptake and a 24mm sclerotic lesion of the right intertrochanteric femur.

Fig. 3.

PSMA PET-CT – Coronal View Axillary Lymph Node

Coronal view PSMA PET-CT demonstrating an enlarged left axillary lymph node measuring 35mm on the short axis with an SUV max of 4.1.

To further evaluate the femoral lesion initially found on the PSMA PET-CT, a whole-body PET-CT was done. This imaging study confirmed the initial scan and revealed a 24mm fluorodeoxyglucose (FDG)-avid right sided proximal femoral sclerotic lesion. The differential for this lesion included metastatic melanoma, metastatic prostate carcinoma, and a chondroid bone lesion. The histology of the femoral sclerotic lesion was not determined prior to the patient's death.

For management of the clear cell renal cell carcinoma, the patient underwent a right robotic-assisted radical nephrectomy. Thereafter, the patient underwent a left axillary lymph node resection for the concurrent metastatic melanoma which was found to be originating from the right elbow. Further management of the primary melanoma included radiation therapy to the primary site. Unfortunately, the patient succumbed to the malignancies several months after his initial diagnosis.

3. Discussion

This case report details the clinical course of a 76-year-old male with the rare occurrence of concurrent metastatic melanoma, prostate cancer, and clear cell renal cell carcinoma, all uniquely identified through the use of PSMA PET-CT. The existence of three distinct malignancies in a single patient poses a significant challenge in diagnosis and management, and the novel use of the PSMA PET-CT in this case demonstrates the diagnostic importance of advanced imaging, specifically in the urological field. Subsequent to the diagnosis of all three primary malignancies, the challenge of this case was to devise a comprehensive treatment plan that would address each of the three malignancies while keeping our 76-year-old patient's limitations in mind.

A review of the literature revealed no documented cases with the exact combination of metastatic melanoma, clear cell renal cell carcinoma, and prostatic carcinoma in a single patient. However, there was one case of prostate cancer, chronic myelogenous leukemia, and multiple myeloma in an 85-year-old male.⁹ While the occurrence of three primary malignancies in one patient is uncommon, the identification of non-prostatic cancers using PSMA PET-CT is increasingly recognized. This case underscores the importance of expanding and improving our repertoire of diagnostic tools. Furthermore, clinicians must keep the possibility of multiple primary malignancies in mind, especially in elderly patients undergoing imaging for a known cancer.

This case contributes to the growing evidence of the role PSMA PET-CT plays in identifying non-prostatic malignancies. In concurrence with the existing literature, we have demonstrated that PSMA PET-CT is not merely an advanced imaging modality unique to prostate cancer, but also demonstrates potential for a broader application to general oncological diagnostics. Furthermore, this case highlights the importance of a holistic and multidisciplinary approach to treating patients presenting with several primary malignancies. Future research should focus on establishing the complete applications of PSMA PET-CT in the field of urological oncology, specifically which malignancies it is capable of detecting. Such investigations are already underway including a multi-institutional clinical trial evaluating the therapeutic potential of radioligand-tagged PSMA for metastatic renal cell carcinoma.^10,11

4. Conclusion

There is a paucity of reported cases on the rare occurrence of three primary malignancies in a single patient, specifically the triad seen in this case. Furthermore, the identification of non-prostatic cancers using PSMA PET-CT in this case adds to the increasing amount of literature supporting its broader application.

Disclosures

The authors report no conflicts of interest or associated disclosures.

Funding

The authors report no financial support for this study.

CRediT authorship contribution statement

Eylon J. Arbel: Writing – review & editing, Writing – original draft, Visualization. Brian F. Dinerman: Writing – review & editing, Writing – original draft, Visualization, Supervision, Conceptualization. John M. Rutkowski: Writing – review & editing, Writing – original draft, Visualization, Project administration, Data curation, Conceptualization.