Angiographically cryptic AVM presenting as a pontine tumor

A 19-year-old child became disoriented and ataxic 6 days after a diphtheria-pertussis-tetanus (DPT) booster injection. Computerized tomographic scan revealed a hyperdense mesencephalic-pontine mass, and angiography demonstrated an avascular mass. Pontine biopsy revealed no abnormality. Her clinical course fluctuated until her death 15 months later. At autopsy, an angiographically cryptic arteriovenous malformation (AVM) was present in the mesencephalon and pons. Vascular malformations of the brain stem producing prolonged clinical courses, are reviewed.