Challenges in developing a digital pathology consultation network: insights from the MELCAYA experience

Objectives: The increasing adoption of Whole Slide Image (WSI) technology has created new opportunities for collaboration in diagnostic pathology. This study aims to describe the development, implementation, and challenges of establishing a second-opinion platform for pathology revision, focusing on improving the diagnostic assessment of melanoma in children, adolescents, and young adults (CAYA). Methods: Two-hundred-eight melanomas and atypical melanocytic lesions from CAYA patients were retrospectively collected, resulting in 311 associated WSIs. Recognizing the rarity of these cases, patient enrollment was distributed across 11 centers spanning 6 European countries. All slides were digitalized at each participating institution and uploaded into a centralized digital platform to be reviewed. Results: A total of 144 WSIs (46.3 %) exhibited technical defects, classified as critical, major, or minor based on their impact on WSI quality and visualization. Of these, 101 (70.1 %) showed analytical defects, while the remaining 43 (29.9 %) presented pre-analytical issues. Significant inter-center variability in file sizes was observed, reflecting differences in scanning protocols and tissue processing. Twenty-four cases (11.5 %) exhibited major discordances on melanoma vs atypical melanocytic lesions classification, underscoring the importance of centralized pathological review. Discussion: This study highlights the challenges of obtaining standardized, high-quality WSIs in real-world settings, particularly due to the rarity of the disease and the limited availability of tissue. Thesefindings reinforce the importance of establishing standardized protocols across institutions to provide pathologists with a high-quality repository and improve patient outcome through effective second-opinion reviews.