Protein kinase Cγ antibodies and paraneoplastic cerebellar degeneration

Onconeural antibodies are diagnostic markers for paraneoplastic neurological syndromes and indicate the underlying tumor type. Recently, a new antibody against protein-kinase Cγ (PKCγ) was detected in a patient with paraneoplastic cerebellar degeneration (PCD). We report here a second patient. A 70-year-old woman presented with cerebellar ataxia, dysdiadochokinesia, and dysarthria. Her serum showed immunoreactivity against the cytoplasm, dendrites and axons of Purkinje cells in tissue-based screening, later confirmed by immunoblot and phage plaques as anti-PKCγ. Tumor search revealed an adenocarcinoma of hepatobiliary origin. Detection of PKCγ antibodies should be considered in PCD and adenocarcinoma without typical onconeural antibodies.