Three cases showed many plasma cells infiltrated in lamina propria.Endothelial swelling of small blood vessels and syphilitic vasculitis were also observed.

• 3例直肠壁黏膜固有层内均有大量浆细胞漫润，小血管内皮细胞肿胀及梅毒性小血管炎，直肠黏膜表面溃疡，大量浆细胞、淋巴细胞、组织细胞漫润；