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.
Also known as Cyst Of Kidney and Simple Renal Cyst. A cyst is a fluid-filled sac. There are two types of kidney cysts. Polycystic kidney disease (PKD) runs in families. In PKD, the cysts take the place of the normal tissue. They enlarge the kidneys and make them work poorly, leading to kidney failure.