Anti-Yo-Associated Paraneoplastic Cerebellar Degeneration Manifesting as Acute Cerebellitis with Posterior Cranial Fossa Hypertension

BACKGROUND: Paraneoplastic cerebellar degeneration (PCD) is a rare complication of some malignant cancers. It is most commonly described in women with gynecologic or breast malignancies; however, there have been reports in other types of cancers. Symptoms include ataxia, dysarthria, and tremors, which could be the first manifestations of an underlying malignancy. CASE DESCRIPTION: A 50-year-old woman had an acute PCD with anti-Yo antibodies from an underlying breast invasive ductal carcinoma. She presented with intracranial hypertension in the posterior cranial fossa that required an emergent decompressive craniectomy. CONCLUSIONS: PCD is an uncommon disease that may manifest initially as posterior cranial fossa hypertension and subsequent acute hydrocephalus owing to diffuse cerebellar swelling. To our knowledge, this is the first described case of an anti-Yo PCD that has manifested as acute posterior cranial fossa hypertension owing to diffuse cerebellar edema. Early diagnosis and treatment should be pursued to improve long-term outcomes.