RESUMO
Anti-Yo-associated paraneoplastic cerebellar degeneration (PCD) syndrome is a very rare condition that is most commonly associated with breast and gynecologic cancers. Those cases associated with breast cancer tend to be human epidermal growth factor receptor 2 (HER2)-positive, though the reason for this correlation is unknown. Most commonly, the neurologic symptoms of the PCD syndrome predate the patient's cancer diagnosis. Thus, prompt diagnosis of PCD is essential to allow for early treatment of the neurologic symptoms and the underlying malignancy. However, the prognosis is very poor for the anti-Yo-associated paraneoplastic syndrome, since neurologic damage is usually rapid and irreversible. Further progression may be stopped with appropriate treatment of cancer, but existing neurologic deficits at the time of diagnosis are usually permanent. Steroids, plasma exchange, and rituximab are commonly used treatments, though these have had mixed to poor results.