Case report: tumefactive demyelinating lesions after the second cycle of alemtuzumab in multiple sclerosis; immune cell profile and biomarkers

We present a case of multiple tumefactive demyelinating lesions (TDLs) emerging 24 months after the second cycle of alemtuzumab treatment. A woman with relapsing-remitting multiple sclerosis (MS) discontinued fingolimod treatment due to gestational desire, which resulted in a severe disease exacerbation. Alemtuzumab was initiated, accompanied by regular clinical, radiological, and immunological monitoring. She relapsed prior to the second cycle, exhibiting 12 T1Gd lesions, and peripheral blood showed an increase in B-cells and a decrease in T-cells. At 24 months following the second cycle, she developed cognitive impairment and multiple T1Gd lesions, including TDLs, were evident on the brain MRI. We found not only an increase in B-cells but also in Th1 central memory cells. Th1/Th17 cells increased 3 months before the detection of TDLs. TDLs can appear 24 months after the second cycle of alemtuzumab treatment in MS. The increase in Th1/Th17 cells could be a candidate biomarker for TDLs in alemtuzumab-treated MS patients.