The early diagnoses and treatment of anti-Yo antibody-mediated paraneoplastic cerebellar degeneration in a patient with breast cancer: a case report.

Background: Paraneoplastic cerebellar degeneration (PCD) is a relatively rare complication among patients with cancers with nonmetastatic tumor manifestation, including breast cancer. A breast cancer diagnosis is usually made several months (or even years) after the onset of neurological symptoms. Case Description: In this study, we describe the early diagnosis and treatment of PCD in one patient with breast cancer. The patient's first symptom was unsteady gait, followed by dizziness and dysarthria of explosive speech. Subacute progressive ataxia symptoms, weight loss, normal imaging findings, and a lack of evidence of infection combined to lead to clinical diagnosis of PCD, and further confirmed by positron emission tomography-computed tomography (PET-CT), positive anti-Yo antibodies and core needle biopsy. Immunosuppressant therapy consisting of intravenous immunoglobulin (IVIG) and high-dose corticosteroids was effective. The patient underwent modified radical mastectomy and 2 cycles of chemotherapy, and the result suggested that treatment of the primary tumor also improved the neurological symptoms to a certain extent. At 1-year follow-up, there was no evidence of recurrence, and the patient's neurological symptoms were stable. Conclusions: Once PCD was suspected, without clear physical findings or symptoms, PET-CT should be performed for a systemic evaluation for an occult malignancy. Even if the diagnosis and treatment were timely, expectations for prognosis should not be too high.