Paraneoplastic Cerebellar Syndrome Presented as Cerebellar Hypermetabolism in a Patient With Occult Breast Carcinoma

A 47-year-old woman presented with an acute cerebellar syndrome. Neither cerebellar atrophy nor an infarction or tumor was shown on MRI. A diagnostic CT demonstrated enlarged axillary lymph nodes, but no primary tumor. Puncture of these nodes showed non-small cell carcinoma. 18F-FDG PET/CT imaging was performed and suggested an occult breast carcinoma, which was confirmed by pathological examination. It also showed cerebellar hypermetabolism, consistent with a PCS (paraneoplastic cerebellar syndrome). This case shows that 18F-FDG PET imaging may be of value in patients in which a PCS is considered clinically, particularly in patients suspicious for an occult malignancy.