Paraneoplastic cerebellar degeneration with anti-Yo antibody in a patient with HER2/neu overexpressing breast cancer: A case report with a current literature review

Paraneoplastic cerebellar degeneration (PCD) is a rare paraneoplastic syndrome, occurring in <1% of breast cancers. We describe a 32-year-old female presenting with ataxia subsequently diagnosed with poorly differentiated breast cancer. She was serum anti-Yo antibody positive, with estrogen/progesterone receptor negative and HER2/neu receptor positive breast cancer. Neurological symptoms progressed despite modified radical mastectomy, supraclavicular lymphadenectomy, intravenous immunoglobulin, corticosteroids, transtuzumab, and combination chemotherapy. We performed a literature search, which found a possible association between anti-Yo positive PCD and HER2/neu-expressing breast cancer.