Immunohistochemical staining of bone marrow sections from patients with acute myeloid leukemia (AML) at presentation (A and C) and control patients (B and D) using antibodies against thrombomodulin (TM) (A and B) and von Willebrand factor (vWF) (C and D).

Note that endothelial cell sprouts and small microvessels without visible lumina were prevailing in AML sections (red staining in A and C), contrasting with big and well-shaped vessels in the controls (B and D). Original magnification ×500.