Immunological mechanisms in opsoclonus-myoclonus associated neuroblastoma.

Opsoclonus-myoclonus syndrome is a rare paraneoplastic disorder, often associated with malignancies including neuroblastoma (NB), the most common solid tumor of childhood derived from the sympathetic nervous system. The pathogenesis of this syndrome is still undefined but is suspected to be the result of an autoimmune response. In this respect, different autoantibodies binding to neurons or cerebellar Purkinje cells have been detected in OMS-associated NB. In addition, immunohistochemical analysis of NB affecting children with OMS demonstrated the presence of interstitial or perivascular lymphoid infiltrates resembling secondary lymphoid follicles. Immunophenotyping of these lymphoid cells showed the existence of a mesh of CD21(+) follicular dendritic cells, numerous CD20(+) B lymphocytes in the germinal center and the mantle zone of the follicle and few CD3(+) T lymphocytes in a perifollicular area. Since information is lacking about the mechanism involved in ectopic lymphoid neogenesis of OMS-associated NB, we are currently investigating the role of different chemokines and their cognate receptors in the recruitment of lymphoid cells within tumor mass of OMS-associated NB. Here, we review some recent data about the pathogenesis of OMS-associated with NB.