Study of significance of bone marrow microvessel density in myeloproliferative neoplasms in correlation with CD34 blasts, mast cell count and fibrosis

Myeloproliferative neoplasms (MPN) are clonal hematopoietic stem cell diseases characterised by myeloid cell growth from one or more lineages. Angiogenesis, in contrast to other subtypes, plays a substantial role in the pathophysiology of primary myelofibrosis (PMF). Research expressing the correlation of microvessel density (MVD), blasts, fibrosis and mast cell count in MPN cases are rarely conducted. We aimed to study the significance of MVD in correlation with CD34 blasts, mast cells and fibrosis in bone marrow biopsies of MPN patients.

Increased MVD score was mostly associated with PMF subtype among all the MPNs. Further, higher MVD was observed to be associated with increased blast count and poor prognosis. With angiogenesis playing a critical role in disease outcome, we now have drugs to regulate angiogenesis that are supported by contemporary research. However, further studies with larger cohorts to establish the theranostic role of MVD in MPNs is recommended.

The current research was a cross sectional study conducted on 66 cases diagnosed as MPN during a six-year period. This comprised of 32 chronic myeloid leukemia (CML), 31 PMF and three essential thrombocythemia (ET) cases. Routine staining along with reticulin stain to look for fibrosis and immunohistochemistry (IHC) using CD34 and mast cell tryptase (MCT) were performed.

We found increased MVD in PMF, when compared to CML and ET (p = 0.042). Further, mean MVD was observed to be increased with high blast counts (p = 0.036). On follow up, raised mean MVD was seen in those cases with relapse/deceased as compared to disease-free patients, which was highly significant (p = 0.000). Conclusions: Increased MVD score was mostly associated with PMF subtype among all the MPNs. Further, higher MVD was observed to be associated with increased blast count and poor prognosis. With angiogenesis playing a critical role in disease outcome, we now have drugs to regulate angiogenesis that are supported by contemporary research. However, further studies with larger cohorts to establish the theranostic role of MVD in MPNs is recommended.