Fig. 2
The renal biopsy specimen in case 2 contained 43 glomeruli, with no major glomerular changes except three with global sclerosis. a Periodic acid-Schiff (PAS) stain (100 ×) showed inflammatory cell infiltrate in tubules and interstitium. b PAS stain (400 ×) showed infiltration of lymphocytes and plasma cells (yellow arrows) in interstitium. c Immunohistochemistry for IgM (400 ×) suggested the presence of IgM-positive plasma cells in tubules and interstitium. The average number of IgM-PCs in three HPFs was 32. d Clinical course in case 2: After the patient received methylprednisolone (mPSL; 500 mg daily) intravenously for three consecutive days, she started on prednisolone (PSL; 35 mg daily; 0.6 mg/kg/day), and disease markers decreased immediately. Thus, we gradually tapered and discontinued PSL treatment as shown here. Three months after PSL discontinuation, serum IgM, proteinuria, and urinary β2-microglobulin (u-β2MG) levels increased. Therefore, PSL 20 mg daily (0.35 mg/kg/day) was administered and disease markers improved