Multi-Lineage Differentiation Drives Hamartoma Formation in Large-to-Giant Congenital Melanocytic Nevi: Evidence for Nevocyte Multipotency

A total of 276 CMNs of different sizes were involved in this study. LGCMN cases with diverse hamartomas were identified and analyzed by histology and immunofluorescence. Whole-exome sequencing (WES) of matched normal skin, LGCMN, and hamartoma tissues assessed mutational overlap. RNA-seq, immunohistochemistry, and immunocytochemistry evaluated multipotency pathways and stem markers across CMN sizes. LGCMN and SMCMN cells were assayed for clonogenicity and induced to differentiate along osteogenic, chondrogenic, adipogenic, and neurogenic lineages in vitro. 3D spheroid cultures and cell-derived xenograft (CDX) models tested LGCMN multi-lineage differentiation in vivo. Single-cell RNA-seq of patient-derived hamartomas delineated intermediate differentiation states and active pathways.