There are many reasons for having a cyst on the spleen, usually related to parasitic infection, metabolic abnormality, trauma and other factors. 1. Parasitic infection: clinically known as parasitic cysts, related to the infection of parasites, when the parasites enter the cystic tissues will form a mass, which will cause splenic cysts. 2. Abnormal metabolism: when the metabolic function of human body is abnormal or metabolic function decreases, and blood circulation is poor, it will form splenic stasis, which may eventually cause splenic cysts. 3. Trauma: usually seen in pseudocysts, if trauma occurs without timely treatment, it may cause splenic bruising, and when the bruising cannot be absorbed by itself, cysts will be formed. It is recommended that patients go to regular hospitals in a timely manner, and actively diagnose and treat under the guidance of professional physicians to avoid adverse consequences.