Paraneoplastic cerebellar degeneration with anti-Yo antibodies and an associated submandibular gland tumor: a case report.

Background: As a debilitating syndrome, paraneoplastic cerebellar degeneration (PCD) remains challenging to treat. Further, anti-Yo antibody (directed against human cerebellar degeneration-related protein 2) detection in patients with PCD is associated with unsatisfactory responses to existing therapies. Here, we present the case of a 60-year-old woman who developed PCD with anti-Yo antibodies and a submandibular gland tumor.

Case Presentation: A 60-year-old woman presented with a 5-day history of unsteadiness of gait and inadequate coordination of her extremities, along with truncal instability. Although walking without aid was possible, dysmetria of all four limbs, trunk, and gait ataxia was observed. While routine biochemical and hematological examinations were normal, the patient's blood was positive for anti-Yo antibodies. When the neurological symptoms deteriorated despite administration of intravenous methylprednisolone, fluorodeoxyglucose-positron emission tomography (FDG-PET) and computed tomography (CT) images with contrast enhancement were performed, which showed a tumor in the left submaxillary gland. She underwent total left submandibular gland resection, including the tumor; histological and immunohistochemical results revealed a salivary duct carcinoma. She was administered intravenous methylprednisolone, followed by 10 plasma exchange sessions, intravenous immunoglobulins, and cyclophosphamide therapy. Following treatment, her symptoms were not alleviated, even after the reduction of anti-Yo titers.

Conclusions: Although tumor detection was delayed, early tumor detection, diagnosis, and PCD treatment are essential because any delay can result in the progression of the disorder and irreversible neurological damage. Therefore, we recommend that the possibility of a salivary gland tumor should be considered, and whole-body dual-modality CT, including the head and neck, and FDG-PET should be performed at the earliest for patients with well-characterized paraneoplastic antibodies when conventional imaging fails to identify a tumor.