Targeted fresh biopsy samples from each examined site were fixed in 10% pH neutral formalin, and embedded in paraffin. Slides of 4-um sections were deparaffinized and hydrated. After antigen retrieval and blocking procedures, Immunology and Histology Chemistry (IHC) staining for CD34 was performed by mouse anti-CD34 monoclonal antibody (ZM-0046, ZSGB-BIO, Beijjing, China) as per the manufacturers' instructions.