Immunological abnormalities in opsoclonus cerebellopathy

Opsoclonus and other cerebellar symptomatology developed in a patient who underwent mastectomy for adenocarcinoma of the breast. No evidence for metastases was found. Immunological studies demonstrated decreased function of T suppressor cells and hyperreactivity of T helper cells in spite of a normal suppressor/ helper ratio. The clinical condition, as well as the immunological abnormalities normalized under steroid treatment. An autoimmune process as etiopathogenesis of this paraneoplastic syndrome is proposed.