Fig. 1

Clinical course. In 2014, an induction therapy consisting of 4 cycles of 21-day bortezomib plus a dexamethasone (BD) regimen (intravenous bortezomib 1.3 mg/m² on days 1, 4, 8, and 11; and oral dexamethasone 20 mg/day on days 1, 2, 4, 5, 9, 11, and 12) was administered. Granulocyte-colony stimulating factor (G-CSF) with peripheral blood stem cell harvesting (PBSCH) and melphalan (MEL) with auto- peripheral blood stem cell transplantation (PBSCT) were performed subsequently. In auto-PBSCT, a total of 200 mg/m² MEL was administered over two consecutive days (100 mg/m²/day) as a conditioning prior to auto-PBSCT. Thalidomide (THAL) 100 mg/day was given as maintenance therapy until it was stopped due to side effects. In 2018, a maintenance therapy consisting of 28-day lenalidomide plus a low-dose dexamethasone (Ld) regimen (lenalidomide 10 mg/day on days 1–21 plus dexamethasone 20 mg/d; days 1, 8, 15, and 22) was initiated. After diagnosis of myasthenia gravis with anti-muscle-specific tyrosine kinase antibodies (MuSK-MG), oral prednisolone (PSL) 5 mg daily was started