Microvessel density in the bone marrow from 62 patients with acute myeloid leukemia (AML) at presentation and from 22 control patients.

Microvessel quantification was performed in adjacent sections of each bone marrow biopsy stained in parallel for thrombomodulin (TM) (A) and von Willebrand factor (vWF) (B) as described in “Materials and methods.” Data are presented as individual values (open circles) and interquartile ranges (boxes). The difference in microvessel counts between the 2 groups was statistically significant (P < .0001 for TM as well as for vWF; Mann-Whitney rank sum test for independent groups).