Schwannian Development in Neuroblastic Tumors

Peripheral neuroblastic tumors consist of two main cell populations: neuroblastic/ganglionic cells and Schwann cells. As described above, the International Neuroblastoma Pathology Classification uses morphological features of both neuroblastic differentia tion and Schwannian stromal development for defining maturational sequence of the pNTs. Based on em-bryological interactions between normal neuroblasts and Schwann cells (Reynolds and Woolf 1993), some postulate that neoplastic neuroblasts produce Schwann cell mitogens important for their proliferation and development (Ambros 2001). Schwann cells, in return, can secrete anti-proliferative and differentiation-inducing factors crucial to neuronal differentiation. This mutual interaction between neuroblastic cells and Schwannian stromal cells may explain the maturational processes of biologically favorable pNTs. In biologically unfavorable pNTs, there is generally less Schwannian component and limited tumor maturation. The origin of the tumor Schwann cells remains controversial. One study indicates that both cell types, i.e., neuroblastic/ganglionic cells and Schwann cells, arise from the same neoplastic neu-roblastic clone or precursor cell (Mora et al. 2001); however, other studies present evidence to support that the Schwann cells in pNTs are reactive in nature and probably recruited from surrounding non-neo-plastic tissue by tumor neuroblastic cells (Ambros et al. 1996).

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