PMC9676962_01
PMC9676962_02
Comparison of the histological features of adult-like MF and PedIMF in this cohort adult-like MF demonstrated higher cellularity (90% in average, A, H&E, x20), frequent clustering of megakaryocytes (B, H&E, x400), with either hyperplastic/bulbous (upper left inset) or dysmorphic (bottom left inset) forms. Moreover, the increase in reticulin was generally high (2 +- 0.82, C, H&E, x100) with frequent thickening and intersection of fibers (upper right inset), with prominent microvascular proliferation (CD34 IHC, D, x200) and occasional intrasinusoidal hematopoiesis (upper left inset) but relatively preserved percentage of infiltrating T lymphocytes (8.3% +- 7.9, CD3 IHC, E, x100). On the other hand, PedIMFshowed a variable cellularity, ranging from 90% to 20% (F, H&E, x20), with almost normal or rarely hyperplastic megakaryocytes (G, H&E, x500), relatively lower increase in reticulin (1.29 +- 0.76, H, H&E, x100) with only occasional intersection of fibers (upper right inset). Microvasculature was often preserved (CD34 IHC, I, x200) and a significant increase in the T lymphocytes infiltration, often arranged in aggregates, was noted in the majority of cases (13.6% +- 7.5, CD3 IHC, J, x100).
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PMC9676962_02_fped-10-1031687-g002.jpg
F2
Adult-like and PedIMF are reported in Figure 2. Adult-like MF showed an increased cellularity per age (n = 3, 75%), with an average of 90% as compared to the adipose component, moderate increase in marrow fibrosis (MF 2 +- 0.82) and prominent vascularity frequently associated with intrasinusoidal hematopoiesis (n = 3, 75%) (Table 4, Cellularity and stromal changes section).