Dermatofibroma are common benign skin tumours that cause lumps in the skin and frequently cause concern upon discovery. The causes of dermatofibroma may include a reaction to trauma such as insect bites but the precise cause is often unclear.
Causes. It's not clear what causes simple kidney cysts. One theory suggests that kidney cysts develop when the surface layer of the kidney weakens and forms a pouch (diverticulum). The pouch then fills with fluid, detaches and develops into a cyst. 1  Symptoms. 2  Risk factors.
Complex kidney cysts are so-called because of their irregular shape. Another difference between simple and complex cysts is that complex kidney cysts often have âenhancedâ tissue, meaning that within the cyst, there is tissue that has access to a blood supply. Most of the time simple cysts are asymptomatic and are not harmful. Sometimes, they may cause pain if cysts enlarge to the point where they encroach on other organs. In other cases they may become infected or may bleed. It is rare for simple kidney cysts to cause any reduction in kidney function. However, there is a link between simple kidney cysts and high blood pressure, although it is unknown whether the link is a causative link or simply correlation.