Updated project metadata. The remarkable plasticity of Schwann cells (SCs) is essential for nerve regeneration but also contributes to neuropathies and cancer progression. It has not yet been investigated whether the adaptive potential of SCs is manifested in stromal, tumor associated SCs characteristically found within a benign subtype of neuroblastic tumors (NBTs). We here performed transcriptome profiling of human NBTs, rich and poor in SC stroma, as well as human injured nerves, rich in repair SCs, revealing that stromal SCs exhibit a repair SC characteristic gene expression signature. In turn, primary repair SCs had a pro-differentiating and anti-proliferative effect on NBT cell lines after direct and trans-well co-culture. Within the pool of secreted stromal/repair SC factors, we identified EGFL8, a matricellular protein with so far undescribed function, to induce neuronal differentiation of aggressive NBT cells. EGFL8 expression further correlated with favorable tumor stage and increased patient survival. Our findings suggest that stromal SCs exert nerve repair associated functions in the tumor-environment and underline the therapeutic value of SC-derived factors for aggressive, SC stroma-poor NBTs.