Applicability of Novel Laser Scanning Microscopy Techniques in Demonstrating Characteristic Features of Porokeratosis: In Vivo and Ex Vivo Investigation

ABSTRACT Background Porokeratoses represent a group of keratinization disorders characterized histopathologically by the presence of a cornoid lamella. The recognition of porokeratosis as a genodermatosis, along with its association with increased risk of skin cancer, underscores the importance of accurate and timely diagnosis. Clinical diagnosis can be challenging, often requiring confirmatory skin biopsies. Objectives We aimed to compare traditional diagnostic methods including dermoscopy and conventional histopathology with advanced laser microscopy including reflectance confocal microscopy (RCM) and multiphoton microscopy (MPM) for diagnosing porokeratosis. Methods Seven patients with various clinical types of porokeratosis, two patients with psoriasis vulgaris, and one patient with lichen planus underwent clinical evaluation, dermoscopic examination and in vivo imaging with RCM. Subsequently, punch biopsies were performed for routine histopathological examination and for ex vivo MPM analyses. Data obtained from RCM and MPM were compared with histopathological findings to assess the diagnostic value and accuracy of these advanced imaging modalities. Results The parakeratotic cornoid lamella, a hallmark histopathological feature of porokeratosis, was successfully identified in all examined subtypes of porokeratosis while lacking in control samples using both RCM and MPM. Notably, MPM based on imaging autofluorescence demonstrated a superior capability compared to RCM in visualizing individual parakeratotic cells, highlighting its enhanced potential for detailed morphological assessment in porokeratosis diagnostics. Conclusions Although novel laser microscopy techniques require investments in training, workflow adjustments and time to master, they demonstrate significant potential as noninvasive diagnostic tools for porokeratosis, potentially minimizing the need for invasive biopsy procedures.