Osteolytic Bone Lesions in Patients with Primary Myelofibrosis: A Systematic Review

Background:

Philadelphia negative Myeloproliferative neoplasms classically characterized by excess production of terminal myeloid cells in the peripheral blood. Among this group, primary myelofibrosis is the least common and usually carries the worst prognosis. Bone involvement in primary myelofibrosis has many forms and tend to manifest as osteosclerotic lesions in vast majority of cases, however osteolytic lesions are reported in exceptional occasions. In this review, we tried to shed the light on this rare association.

Methods:

We performed a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched the English literature (Google scholar, PubMed, and SCOPUS) for studies, reviews, case series, and case reports about patient with myelofibrosis who develop lytic bone lesion. We used the terms in combination: "Myelofibrosis'" or "Primary myelofibrosis" OR "chronic idiopathic myelofibrosis" OR "agnogenic myeloid metaplasia" and "Osteolytic bone lesion", "Osteolytic lesion", "lytic bone lesion". The review included patients with primary myelofibrosis confirmed by biopsy. The reference lists of the included studies were scanned for any additional articles. The search included all articles published up to 10th April 2021. Two independent reviewers screened the titles and abstracts of the records independently and papers unrelated to our inclusion criteria were excluded. A total of 13 articles were included in the review.

Results :

Total of 13 patients were included in the review. 7 patients were males, male to female ratio almost of 1:1. The mean age at time of diagnosis was 57.69 year, only two cases were diagnosed at young age, however the majority have osteolytic bone lesion at age above 50 years (12/13) of cases.

The mean time between the diagnosis of primary myelofibrosis until the osteolytic bone lesion capturing was approximately 8.8 years. 9 out of 13 patients have painful bone lesion, others were incidental finding during a scan for other reasons. All patients have significant splenomegaly. All patients had the lytic lesion detected on x ray, and 2 patients had confirmed findings on magnetic resonance imaging (MRI). The most common affected bones were the vertebrae, pelvis, ribs, humerus then the scapula, femur and skull and less frequently wrist bones and calcaneus. Only one case has reported involvement of the tibia and fibula. The shape, the extension and the numbers of lesion were variable, some showed cortical sparing and others come with cortical destruction. 10 out of 13 cases have confirmed the nature of the osteolytic lesion containing hematopoietic stem cells with or without fibrosis, 2 cases were positive for JAK2 mutation. 2 patients have received ruxolitinib, one of them preceded with bone marrow transplant, others received nonspecific therapies.

Discussion:

The hyperdynamic ineffective bone marrow can have a negative impact on the bone structure resulting in different types of bone pathology including lytic and sclerotic lesions.

The exact mechanism beyond developing lytic lesions is not fully studied, observations revealed two possible causes: systemic inflammation and direct mechanical compression from para-osseus lymph nodes.

Lesions prevalence was equal in both genders which can be attributable to a small sample size, in addition, most of the patients were in advanced stages when the lytic lesions discovered and this observation can be explained by the needed time to generate extramedullary hematopoiesis and its subsequent effect on bone structure.

The variation in time between the diagnosis of PMF and development of osteolytic bone lesions could be due to the indolent phase of the disease, in which patients can survive for decades without symptoms.

Until recently the treatment of myelofibrosis was supportive, but after establishing the JAK2-stat pathway role in myeloproliferative disorders the FDA approved ruxolitinib a JAK2 inhibitor which shows not only survival benefit but also has a significant impact on the resolution of the lytic bone lesions as well.

conclusion

Osteolytic bone lesions in patients with primary myelofibrosis is extremely rare finding, and noticed shortly after diagnosis in elderly and after longer duration in young patients. The lytic lesion seems to have a bad prognostic value as we can notice 11 out of 13 patients died within one year of detection.

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