Fig. 1: Spatial transcriptomic profiling and single-cell analysis of primary MCC lesions exhibiting epidermotropism.

A Immunohistochemistry staining for Cytokeratin 20 in sample #2 in 20× magnification with 1 mm scale bar at the bottom right. High power fields (200×, i and ii) highlights epidermotropic MCC cells forming intraepidermal nests, as indicated by arrows, 100 μm scale bars are shown at the bottom right. B UMAP dimensionality reduction of segmented single-cell data inferred from spatial transcriptomic data, colors represent distinct transcriptional clusters. C Spatial mapping of segmented single-cell data with cells color-coded as defined in (B). D Normalized expression of representative gene markers in histomorphologically annotated cell populations: epiMCC epidermal MCC, cMCC tumor core MCC, vasMCC perivascular MCC, bK basal keratinocytes, and sbK suprabasal keratinocytes.