To describe a patient with multiple sclerosis (MS) presenting with chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS).

One previous case report described CLIPPERS-like MRI findings in a patient with MS. CLIPPERS presents with subacute pontocerebellar dysfunction, <3mm nodular perivascular enhancement on MRI, and dense perivascular lymphocytic inflammation with T cell predominance. SLIPPERS has similar findings with supratentorial localization. 

A 38-year-old man diagnosed with MS at age 19 with typical MRI findings and positive oligoclonal bands, presented with bilateral leg weakness, dyspnea, dysphagia, and dysphonia. MRI revealed diffuse enhancing perivascular hyperintensities in the bilateral cerebellum, pons and medullary regions suggesting CLIPPERS. A five day course of solumedrol resulted in complete radiographic resolution of the enhancement. Weakness improved quickly, but dysphonia, dysphagia and dyspnea improved slowly.  He was discharged to an acute rehabilitation hospital.  In retrospect, he had presented in 2015 with profound encephalopathy and expressive aphasia. MRI revealed diffuse cortical and subcortical perivascular enhancing lesions. When extensive serum and CSF studies, including malignancy, infectious, vasculitis, sarcoid, autoimmune and paraneoplastic evaluations were negative, a frontal lobe lesion biopsy revealed perivascular T-cell predominant infiltrate without evidence of infection. Pathology reports from CDC and local institution supported an inflammatory process and did not imply it was related to patient’s known MS.  Methylprednisolone treatment resulted in slow clinical and radiographic improvement. This event may have represented what is now known as SLIPPERS, unrecognized as the supratentorial variant of CLIPPERS was first reported a month earlier.

Patients with MS can present with CLIPPERS/SLIPPERS like events including supportive MRI, pathology, and treatment response. CLIPPERS/SLIPPERS require careful exclusion of alternative diagnoses, particularly when confounded by pre-existing MS.