Postimmun acute necrotizing hemorrhagic encephalopathy

This code represents a severe, acute inflammatory encephalopathy characterized by widespread necrosis and hemorrhage in the brain, occurring as a rare adverse reaction following immunization. It is a life-threatening condition involving rapid neurological deterioration due to immune-mediated damage to brain tissue and blood vessels.

Use this code for patients presenting with acute onset of neurological symptoms such as seizures, coma, or focal deficits, where diagnostic imaging (e.g., MRI) reveals multifocal hemorrhagic and necrotic lesions, and a clear temporal relationship to a recent vaccination is established. Documentation should explicitly link the encephalopathy to a post-immunization event.

• Ensure documentation clearly states the encephalopathy is "postimmunization" and includes "necrotizing" and "hemorrhagic" features.
• Do not confuse with other forms of acute encephalopathy (e.g., viral, toxic-metabolic) unless the post-immunization etiology is confirmed.
• Sequence this code as the primary diagnosis if it is the reason for the encounter; otherwise, sequence it as a secondary diagnosis following the primary condition.