Voltage-Gated Calcium Channel Antibody-Induced Oropharyngeal Dysphagia Presenting as a Paraneoplastic Neurological Complication in Breast Cancer

Paraneoplastic neurologic syndromes (PNS) are a group of disorders characterized by an autoimmune response against the nervous system due to cross-reactivity between malignant and normal neural tissue. The most commonly associated malignancies include small cell lung cancer, ovarian cancer, breast cancer, and lymphoma. Multiple PNS have been reported including paraneoplastic cerebellar degeneration, retinopathy, sensorimotor peripheral neuropathy, encephalopathy, opsoclonus-myoclonus syndrome, and stiff-person syndrome. We report a case of a 67-year-old woman with breast cancer who presented with a history of progressive oropharyngeal dysphagia as a paraneoplastic neurologic complication. She was diagnosed with invasive ductal carcinoma, nuclear grade 3 with moderate peritumoral lymphoid infiltrate. Hormone receptors were weakly positive for estrogen receptor (ER) (H score 15), weakly positive for progesterone receptor (PR) (H score 30), and negative for human epidermal growth factor receptor 2 (HER-2/NEU). The patient underwent a localized segmental mastectomy but declined any further adjuvant treatment. Three years after being diagnosed with invasive ductal carcinoma of the breast, she developed progressive oropharyngeal dysphagia that warranted percutaneous endoscopic gastrostomy (PEG) tube placement. Testing for onconeural antibodies was positive for voltage-gated calcium channel antibody. An extensive workup was negative for any alternative etiology that would explain her neurological symptoms. The patient declined further treatment and eventually succumbed to her illness.