Paraneoplastic cerebellar degeneration and dermatomyositis as first manifestations of underlying breast malignancy: a report of two cases and a brief review of the subject.

Paraneoplastic syndromes are rare first manifestations of breast cancer. In this report, we present two cases of a 58-year-old woman and a 69-year-old woman presenting with acute symptoms of paraneoplastic cerebellar degeneration (PCD) and dermatomyositis, respectively, as the first sign of breast malignancy. The patient diagnosed with PCD presented initially with ataxia, was serum anti-Yo antibody negative, and subsequently investigated to have poorly differentiated intraductal breast carcinoma. Cerebellar symptoms regressed following breast cancer surgery and chemotherapy, highlighting the better neurological prognosis associated with anti-Yo antibody negative PCD. The rarity of these presentations highlights the necessity to include an occult malignancy in the differential diagnosis when attending to such patients.