J Breast Cancer.  2021 Feb;24(1):106-116. 10.4048/jbc.2021.24.e2.

Paraneoplastic Encephalitis Associated with Locally Advanced Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

• Shay RC
• Diamond JR
• Kagihara JA
• Sams SB

• KMID: 2515172
• DOI: http://doi.org/10.4048/jbc.2021.24.e2

Abstract

Paraneoplastic neurologic diseases (PND) are rare but can occur in patients with common malignancies including breast cancer. In patients with hormone receptor (HR)-negative human epidermal growth factor receptor 2 (HER2)-positive breast cancer, PND have been reported in association with anti-Yo antibodies and with clinical presentation of paraneoplastic cerebellar degeneration. We describe the case of a woman with progressively altered mental status and seizures, ultimately requiring admission. Based on her clinical presentation, imaging findings, and evidence of neural-directed antibodies in her serum and cerebrospinal fluid, she was diagnosed with paraneoplastic limbic encephalitis (LE) due to an underlying HR-negative, HER2-positive breast cancer. She showed a transient response to immunosuppression but had more significant improvement after surgical resection and initiation of chemotherapy along with HER2-directed therapy. To the best of our knowledge, this is the first documented case of paraneoplastic LE in a patient with HR-negative, HER2-positive breast cancer likely caused by the production of an unclassified anti-neuronal antibody.

Keyword

Autoimmunity; Breast neoplasms; ERBB2 protein; human; Limbic encephalitis; Paraneoplastic syndromes; Nervous system