Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids following influenza vaccination

Inflammatory processes within the central nervous system are challenging for the clinician, radiologist, and pathologist alike. They often can mimic other more well-known and defined disease processes. We present the case of a patient with a newly described inflammatory process that primarily involves the pons and adjacent structures, which is called chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS). An 80-year-old man presented with numbness of his right hand that ultimately progressed to involve both lower extremities and face and was associated with mild dysarthria and ataxia. He had received the influenza vaccination 2 weeks prior. The biopsy revealed primarily reactive T-cell lymphocytic infiltrates with macrophages and gliosis. Treatment required long-term immunosuppressive therapy. CLIPPERS is a recently described central nervous system inflammatory condition that should be considered in the differential diagnosis when a prominent lymphocytic inflammatory infiltrate is encountered in brainstem, spinal cord, midbrain, or cerebellar biopsies.