Regression of Myelofibrosis and Osteosclerosis following Hematopoietic Cell Transplantation Assessed by Magnetic Resonance Imaging and Histologic Grading

Patient with complete resolution of myelofibrosis 1 year after transplantation. A, Bone marrow reticulin stain before transplantation. Diffuse reticulin positivity (300×). B, Reticulin stain at 1 year after transplantation (grade 0-1). C, T1 spin-echo (TE) sequence shows progressive diminution of the dark (low signal) medullary pattern (TE 4 homogeneous [H]) and transition to a pale gray (intermediate) pattern typical of more normal marrow at 3 months (TE 2H), and return to near normal, with scattered foci of low signal at 1 year after transplantation (TE 1.5H). This coronal section shows femoral and acetabular regions of the ilia and portions of the lower lumbar vertebrae on a selected image of 20 acquired through the pelvic marrow. D, TE transverse images with the same timing as in C; similar changes from dark to light are seen in the posterior iliac crests. E, STIR images show progression from moderately light (STIR 3, mildly hypercellular) to dark (STIR 0.5, normocellular) with resolution of fibrosis; same time sequence as in C and D.

Patient with refractory disease. A, Bone marrow reticulin stain before transplantation, grade 3-4 fibrosis (300×). B, Reticulin stain 1 year after transplantation; no improvement (fibers are still dense 300×). C, TE coronal MRI sequence documents fibrosis before transplantation (TE 4 homogeneous [H]) with little or no change at 3 months (TE 4H) and 1 year (TE 4 patchy [P]). There is only slight improvement in the femoral head appearance at 1 year. D, TE MRI of posterior iliac crests shows lack of change in improvement of skeletal appearance over 1 year. E, STIR sequence shows only modest change from before transplantation (STIR 3H) to 1 year (STIR 1P). This change was interpreted as primarily due to decreased fluid content without much change in fibrosis. Note fresh needle site on the right side of the left image, with extraosseous and intraosseous edema seen as a bright white linear signal (arrowhead) and a linear vertical line. This image was representative of the marrow as a whole.

Heterogeneous fibrosis, TE coronal view. Heterogeneous pattern with a focal high signal region in the medial right femur (arrow) indicats an area of uninvolved hypocellular normal fatty marrow.

Needle tracks. Old and new needle biopsy sites are visible on TE and STIR sequences (patient 20). A, TE series regressing from TE 4 homogeneous (H) to TE 2H at 1 year. Biopsy sites appear as vertical dark lines (black arrowheads) that remain visible in all 3 images. STIR image regresses from 2H to 1H at 1 year. The right panel (1-year follow-up) shows a new needle track, which is better recognized as new on the STIR image. B, STIR image at 1 year follow-up (compare with A, lower right). A new needle site is identified on the far right (arrow), with a crescent of bright periosteal edema and a linear white line showing the needle track filled with fluid. An old needle site is present on the left side (yellow arrowhead).

Osteosclerosis. A, Before transplantation, an extremely wide trabecular bone with multiple osteoid lines and knobby projections characterizes this patient’s marrow biopsy (osteosclerosis grade 5). B, One year after transplantation, the average trabecular width was within normal limits (osteosclerosis grade 1). Hematoxylin and eosin stain, 250×).

Documentation of fibrosis by vimentin staining. A, Vimentin immunohistology (immunoperoxidase stain) shows the linear staining of fibroblasts and round cytoplasmic staining of other mesenchymal cells before transplantation. B, At 1 year after transplantation, the vimentin staining shows nearly total disappearance of the linear markings of fibroblasts.