A cerebral ring-enhancing lesion carries a long list of differential diagnoses, but in the presence of central diffusion restriction without blood products, the diagnosis of cerebral abscess is most likely. Cerebral abscess is a neurosurgical emergency requiring rapid intervention and drainage.

This case demonstrates the catastrophic consequences of delaying such a life threatening diagnosis. The right periventricular cerebral abscess ruptured into the ventricular system resulting in ventriculitis and leptomeningitis, and active obstructive hydrocephalus with a dismal prognosis.