Introduction: Immunohistochemical studies of paraneoplastic cerebellar degeneration (PCD) are rare, and the findings vary.
Materials and methods: We performed morphological and immunohistochemical characterization of the brain, medulla and tumour of two patients with PCD, Yo antibodies and ovarian adenocarcinoma.
Results: The cerebellum of both patients had extensive loss of Purkinje cells. Microglia activation and T cells were found in the cerebellum, but B cells or deposits of IgG or complement were not detected. Microglia activation was also present in the brain stem and medulla. T cells were found in the ovarian adenocarcinoma.
Conclusion: PCD is characterized by loss of Purkinje cells and microglia activation, and the presence of T cells indicates cellular immune reactions in PCD and in ovarian cancer.