Going out of scope: Slide-free microscopy developments in genitourinary pathology

As digital pathology implementation and artificial intelligence systems become increasingly topical within the field of diagnostic pathology, the question of the next emerging technologies on the horizon may be easy to overlook. While both can be considered as monumental shifts to our field, the larger disruption may be advances in "slide-free" or "label-free" technology that allow for tissue imaging and interpretation without conventional histopathologic techniques reliant on fixation, embedding, sectioning, and glass slides. A number of these technologies have been developed and are capable of generating two-dimensional hematoxylin and eosin-like images of fresh tissue or even three-dimensional renderings of whole specimens. Examples of these technologies include ex vivo confocal microscopy, open-top light-sheet microscopy, non-linear microscopy, stimulated Raman histology, optical coherence tomography, structured illumination microscopy, and others. Considering current developments in artificial intelligence and digital pathology, urologic and male genital system cancers (particularly prostatic adenocarcinoma) have served as a focus for some of the first commercially available technologies achieving regulatory approval for clinical use. As such, genitourinary tissues may also play an important role in the production and testing of slide-free technology. This review explores the last 10 years of expansion in slide-free technology and its specific assessment for applications within genitourinary pathology.