Introduction

While prostate magnetic resonance imaging has gained momentum as a valuable tool to perform target prostate biopsy (PB) and to guide focal treatment of small lesions,^1,2 histopathological evaluation remains the gold standard method for prostate cancer (PCa) diagnosis. In the last year, fluorescence confocal microscopy (FCM), a novel optical technology, has been used for immediate digital image acquisition in an almost hematoxylin-eosin (HE)-like resolution without requiring conventional processing.³ The aim of the present study was to report our first experience using the VivaScope® confocal microscope for intraoperative prostate evaluation and treatment.

Case Report

A 69-year-old patient with low risk PCa (Gleason score 3+3, prostate specific antigen [PSA] 4 ng/ml), treated with external beam radiotherapy and androgen deprivation therapy 12 years prior, presented at our clinic for a progressive increase in PSA serum level up to 7 ng/ml in July 2020. Clinical examination was unremarkable.

Choline positron emission tomography (PET)/computerized tomography (CT) was performed, documenting the presence of a focal area of hyperaccumulation of the metabolic tracer at the level of the prostate left lobe (maximum standardized uptake value 7.6). After discussing all of the available treatment options, the patient was scheduled for salvage prostate cryoablation.

Before proceeding with prostate cryoablation, 3 biopsy cores were taken transperineally under transrectal ultrasound (TRUS) guidance (BK Medical®). Fresh samples were immediately sent for FCM acquisition; the device is located in the urology department. Sample preparation was performed by urologists, and FCM digital images were acquired within a maximum time of 2 minutes for each core. The same specimens were then sent for conventional HE analysis. A single dedicated uropathologist evaluated the obtained images and confirmed intraoperatively the presence of recurrent PCa in 2 out of 3 cores (see figure), and thus we proceeded with the programmed prostate cryotherapy.

Figure. Digital biopsy images. High resolution pictures allow zooming into focal area for better evaluation of prostatic gland architecture.

Specifically, two 2.4 mm cryoprobes were inserted into the prostate. Freezing of the whole gland was obtained using an argon/helium gas-based cyroablation system (Endocare, HealthTronics Inc., Austin, Texas); pressurized argon (300 bar pressure and –180C) achieved freezing, whereas both helium and room temperature were used to obtain thawing. A urethral catheter was placed after the procedure (to be removed 10 days after the procedure), and the patient was discharged on postoperative day 1. Conventional HE analysis confirmed the presence of prostate cancer in the 2 positive cores.

Discussion

The diagnostic accuracy of FCM has been proved to be promising in the dermatological field,⁴ and has also been applied to the interpretation of other human tissues. Recently, PB emerged as a novel promising setting to further evaluate FCM,⁵ and we aimed to test this technology to guide focal treatments for PCa.

To our knowledge, this is the first report on the use of real-time digital pathology in the setting of focal therapies. While questions remain about the accuracy of this procedure to discriminate between Gleason grading groups compared to standard HE images, FCM offers the unique opportunity to evaluate in a few minutes the presence of PCa in prostate biopsy cores. Additionally, once uploaded, FCM images could be shared with remote pathologists, limiting the turnaround time or the need for a pathologist in the operating room.

In conclusion, real-time, intraoperative digital biopsy using fluorescence confocal microscopy is feasible to guide focal treatments in PCa patients.