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Background Perineural invasion (PNI) is a hallmark pathological feature of pancreatic ductal adenocarcinoma (PDAC) and is strongly associated with tumor recurrence, metastasis, and poor survival. However, the spatial cellular architecture and molecular programs driving tumor–nerve interactions remain poorly understood due to limitations of conventional pathology and bulk transcriptomics. This study aimed to systematically characterize the spatial microenvironment of PNI in PDAC and to determine whether distinct tumor molecular subtypes exhibit differential neurotropic invasive capacities.Methods A retrospective cohort of 240 resected PDAC patients was analyzed to evaluate the prognostic significance of PNI. Large-format whole-mount pathology was used to comprehensively visualize tumor–nerve spatial relationships. Subcellular-resolution spatial transcriptomics (Xenium platform) was performed on treatment-naïve PDAC specimens. A large-format multiplex immunofluorescence workflow was established to reconstruct whole-tissue spatial architecture and validate subtype-specific patterns of neural invasion in an independent cohort.Results High-grade intrapancreatic PNI and EPNI were both associated with significantly worse overall survival and disease-free survival ( IDDF2026-ABS-0184 Figure 1(A-D)). Whole-mount pathology enabled panoramic visualization of neural invasion across intra- and extrapancreatic compartments (IDDF2026-ABS-0184 Figure 1(E)). Spatial transcriptomics generated a high-resolution cellular atlas of the PNI microenvironment, identifying diverse cell populations and their spatial organization (IDDF2026-ABS-0184 Figure 1(F,G)). Tumor cells segregated into BSL and CLS subtypes (IDDF2026-ABS-0184 Figure 1(H)). BSL tumors were preferentially enriched in extrapancreatic regions, whereas CLS tumors were more abundant within the pancreas (IDDF2026-ABS-0184 Figure 1(I)). BSL tumors upregulated extracellular matrix remodeling and neurotropic signaling pathways (IDDF2026-ABS-0184 Figure 1(J)). We next developed a large-format multiplex immunofluorescence system that reconstructed the spatial architecture of tumor, nerve, and immune cells within whole sections (IDDF2026-ABS-0184 Figure 1(K)). Applying this approach to 12 PDAC specimens, tumors were classified into BSL, CLS, and mixed subtypes. Notably, BSL tumors exhibited significantly increased nerve density and higher frequencies of PNI both inside and outside the pancreas, whereas CLS tumors displayed a greater abundance of tertiary lymphoid structures (TLS) (IDDF2026-ABS-0184 Figure 1(L-P)).Conclusions Integrated spatial transcriptomics and large-format spatial pathology reveal that basal-like PDAC exhibits enhanced neurotropism and a strong propensity for PNI, whereas CLS displays a more immune-active microenvironment. These findings provide a spatially resolved framework for understanding tumor–nerve interactions and highlight molecular subtype–specific mechanisms underlying neural invasion in PDAC.Abstract IDDF2026-ABS-0184 Figure 1