Publication

Abstract : Background This study compared immunohistochemical markers for angiogenesis in primary myelofi brosis (PMF) and secondary myelofi brosis from various causes. Materials and methods Bone marrow biopsies from 21 patients with PMF, 19 patients with CML-MF, 4 patients with PV-MF and 20 cases of secondary myelofi brosis from miscellaneous causes were stained using anti-CD34 (clone Q-bend, Neomarkers™) immunostaining. Microvessel density (MVD) and microvessel surface area (MSA) were calculated using Image ProPlus™ software. Observations MVD and MSA were markedly increased in BM biopsies from all patients with marrow fi brosis (MF) compared to controls. Differences between groups were statistically signifi cant. Highest mean MVD was seen in PMF, followed by secondary MF, and then by MPNassociated MF. The highest MSA values were seen in PMF, refl ecting the relatively large and abnormally ecstatic blood vessels in this condition. In contrast to MVD, cases with post MPN-MF had the higher mean MSA than secondary MF cases. MVD and MSA in all 3 groups had extensive overlap with each other and also with control bone marrows without fi brosis. The overlap with normal was greatest in the case of secondary MF which also had the most inter-case variability. Discussion Enhanced angiogenesis is believed to be an early and integral part of the epiphenomena associated with PMF and other myeloproliferative neoplasms. This also forms the rationale for use of anti-angiogeneic therapies like Imid’s in PMF. Our fi ndings suggest that the increased angiogenesis may actually be a vital but secondary phenomenon that is common to all forms of marrow fi brosis, and does not necessarily originate from the clonal hematopoiesis of PMF or other myeloproliferative neoplasms. Conclusions While angiogenesis is unlikely to be of use in the histopathological distinction of PMF from secondary myelofi brosis, its enhancement in myriad secondary fi brosing disorders provides interesting insights into the pathogenesis of marrow fi brosis.