A Case of Occult Breast Cancer With Paraneoplastic Polyneuropathy

We encountered a very rarc case of occult breast cancer associated with paraneoplastic sensory polyneuropathy. A 59-year-old woman was admitted to our hospital complaining of numbness in all extremities, ataxia of left extremities and a tumor in the left axilla. From the neurological findings, a malignant tumor was suspected. The immunohistochemical analysis of the axillar swollen lymph node revealed metastasis from breast cancer and confirmed the primary lesion. On a preoperative diagnosis of suspected occult breast cancer, left mastectomy and resection of left axillar lymph nodes were performed. Furthermore, immunohistochemical staining of sural nerves and Western blot analysis of the serum of this patient showed the loss of axons and the presence of antineural antibody in the seurm. Immunological response was considered to be the remote effector system between the breast cancer and sensory polyneuropathy in this disorder.