Abstract
Occult breast cancer (OBC) is a very rare type of breast cancer which accounts for only 0.2% to 0.9% of all breast cancer defined as histologically proven breast cancer found from outside the breast especially axillary with the absence of a primary tumor in the breast. With the development of high-resolution ultrasound, mammography, especially breast-enhanced MRI, the incidence of OBC has decreased in recent years. A standard approach for OBC is to perform a modified radical mastectomy (MRM) at the time of axillary lymph node dissection (ALND). The five-year survival rates after treatment of an occult primary breast cancer with axillary metastases range from 59% to 93%, averaging about 75%. Paraneoplastic neurological syndromes (PNS) are a very rare heterogeneous group of disease caused by mechanisms of the remote effects of malignant tumors other than tumor metastases, infections or side effects of tumor treatment. Malignant tumors with PNS account for only less than 0.01% of all tumors. The treatment of PNS include removal of the tumors and suppression of the immune response. The prognosis of PNS depends on the degree of neuronal damage during the treatment of the disease. PNS is a rare neurological complication in patients with breast cancer and particularly rare in the patients with OBC. Here, we report a rare case of a 62-year-old woman diagnosed as OBC who presented with PNS as the first symptom.