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.
Symptoms. Simple kidney cysts typically don't cause signs or symptoms. If a simple kidney cyst grows large enough, symptoms may include: Dull pain in your back or side; Fever; Upper abdominal pain; When to see a doctor. Make an appointment with your doctor if you have signs or symptoms of a kidney cyst. 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).