case_images: PMC6700296_01
case_images: Vertebral lesions at baseline and during follow-up. (A) Total spine sagittal reconstructions of T1-weighted turbo spin-echo (TSE; left 2 panels), contrast-enhanced water-selective T1-weighted TSE (middle two panels) and T2-weighted sequences (right two panel) at baseline (t = 0) and 10 months (t = 10 mos) after initiation of treatment. At baseline, note the mottled appearance and lower signal intensity of the vertebral bodies on the T1-weighted sequences at baseline. At 10 months after treatment the signal intensity has returned to near normal signal intensity. (B) Zoomed detail of T2-weighted sequences at baseline (left) and 10 months after treatment (right) of the cervical spine. The area outlined by the dashed area at baseline signifies abnormally high signal intensity of the vertebral bone marrow, which returned to normal values at 10 months after treatment.
case_images: fimmu-10-01910-g0001.jpg
case_images: PMC6700296_01_fimmu-10-01910-g0001.jpg
case_images: F1
case_images: During the following months, the constitutional symptoms, and the elevated inflammation markers persisted, and a mild normocytic anemia and leucocytosis developed (Figure 1). The vertebral lesions and epidural mass decreased in size over time (Figure 1) and IgG4 level turned to normal (58 mg/dL) with the patient being in persistent remission on low dose prednisolone.
case_images: Microscopic examination of the lumbar vertebra (biopsy). (A) On overview, the marrow in between the bony trabeculae shows a quite sharp demarcation between normal bone marrow (one third on the left) and the fibrotic lesion (two thirds on the right) (H&E staining, 79x magnification). (B) Higher magnification of the lesion shows fibrosis rich in fibroblasts and arranged in a somewhat storiform fashion with admixed plasma cells and lymphocytes (H&E staining, 400x magnification). (C) Highest magnification shows several fibroblast (arrows), plasma cells (encircled) and lymphocytes (arrow heads) (H&E staining, 800x magnification). (D) Immunohistochemistry for CD138 shows in dark brown the numerous plasma cells (CD138 immunohistochemical staining, 400x magnification). (E,F) Immunohistochemistry for IgG (E) and IgG4 (F) shows in dark brown numerous IgG and IgG4 positive plasma cells, respectively, some of which encircled in red (IgG and IgG4 immunohistochemical stainings, 200x magnification).
case_images: fimmu-10-01910-g0002.jpg
case_images: PMC6700296_01_fimmu-10-01910-g0002.jpg
case_images: F2
case_images: Again, a biopsy was performed, this time of a lumbar vertebral lesion (Figure 2). A quite sharp demarcation was seen between normal bone marrow and the fibrotic lesion (Figure 2A). The fibrosis in this biopsy was comparable to the previous one, but appeared to be more storiform (Figure 2B). The fibrotic focus had a relatively high cellularity, containing fibroblasts, plasma cells and lymphocytes (Figure 2C). Immunohistochemical analysis demonstrated <10% plasma cells in pre-existing bone marrow, but around 25% plasma cells were present in the fibrotic lesion (Figure 2D). Many of the plasma cells were IgG and IgG4 positive (Figures 2E,F, respectively).