During the FCM, basic assessment of the extra-prostatic components AS fatty tissues (Fig. 1a), muscle bundles and nerves (Fig. 2a) was carried out reflectance mode and they are shown in a pink-colour resembling eosin staining (Fig. 1); prostate glandular patterns are clearly different, with a predominant purple colour provided by acridine-stained nuclei (Fig. 3a). PCa is depicted in Fig. 4a. The same H&E features are reported in Figs 1b, 2b, 3b and 4b, respectively. The sample containing PCa was obtained from the patient with extensive extracapsular extension. FCM diagnostic performance in distinguishing between non-prostatic tissue, benign prostatic tissue and PCa was high; FCM demonstrated almost perfect agreement with H&E in its depiction of all tissue types.

The advantages of FCM analysis of peri-prostatic tissue demonstrated in the present study are: fast and simple tissue handling and no need for a dedicated set-up; fast acquisition of high-resolution images similar in appearance to H&E stained images; and instant web availability of images. A weakness of the present study is that only one sample of periprostatic soft tissue contained PCa; however, the issue of PCa detection using FCM has been exhaustively addressed in our previous manuscript [8]. Another limitation of the study is the random fashion of the sampling method; a prospective study is currently ongoing to define the role of systematic sampling of the postero-lateral aspect of the prostate read by FCM to achieve real-time detection of positive surgical margins.