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.
Quick Answer. The cause of kidney cysts is not clear, but medical professionals theorize that the cysts develop when the kidney's surface layer forms a pouch and weakens, according to Mayo Clinic. Cysts develop when the pouch fills with fluid and detaches from the surface layer of the kidneys. Continue Reading.