Osteolytic Lesions in Primary Myelofibrosis and Effect of Ruxolitinib Therapy: Report of a Case and Literature Review.

Here, we report the case of a young female affected by primary myelofibrosis (PMF) who developed an osteolytic lesion of the humerus during the follow-up, and the possible efficacy of ruxolitinib in controlling this rare event. After 26 years of follow-up, the patient reported onset of acute pain at the proximal region of the left upper limb. An X-ray revealed an osteolytic bone lesion in the proximal third of the humeral shaft, which was then confirmed by magnetic resonance imaging. A biopsy of the lytic lesion was done, revealing hypercellular bone marrow with hyperplastic granulopoiesis associated with megakaryocytic proliferation and atypia, accompanied by a diffuse and dense increase in reticulin fibrosis with extensive intersections and coarse bundles of thick fibers, consistent with a grade 3 collagen fibrosis. No new therapeutic intervention was initially required; however, 2 years later, the patient reported symptomatic splenomegaly and drenching night sweats, so ruxolitinib therapy was started. By week 8, the patient had near resolution of constitutional symptoms and a reduction of > 50% of the spleen size that normalized by 6 months; in addition, a repeat bone marrow biopsy showed a decrease in reticulin fibrosis grade. Interestingly, after 9 months of ruxolitinib therapy, further magnetic resonance imaging of the left upper limb showed the absence of bone lytic lesions and a substantial normalization of the bone tissue. In conclusion, with the present case report, we confirm ruxolitinib efficacy in reducing bone marrow fibrosis grade and assume its possible role in the resolution of osteolytic lesions in PMF. Obviously, further studies with a greater number of patients are needed to document the exact frequency of these unusual findings and the possible role of ruxolitinib in their treatment.