The cause of parapelvic or renal cysts is not known, according to Mayo Clinic. Kidney cysts are fluid-filled pouches that form on the one or both kidneys, rarely causing complications.
Unless a parapelvic renal cyst causes complications such as pyelonephritis, symptomatic renal stones or back pain, treatment is not typically required, states the National Institutes of Health. While most kidney cysts don't cause any symptoms, cysts that are large can cause issues including fever, pain in the upper abdomen and dull pain in the back or side, according to Mayo Clinic. The two types of kidney cysts are polycystic kidney disease, or PKD, which runs in families, and acquired cystic kidney disease, or ACKD, which happens in individuals who are undergoing dialysis, explains MedlinePlus.
Symptoms of PKD include pain in the back and lower sides, headaches, urinary tract infections and blood in the urine, states MedlinePlus. ACKD often causes no symptoms, as cysts are normal sized and do not form elsewhere in the body. People with PKD develop cysts that take the place of normal tissue, resulting in enlarged kidneys that do not work properly. Typically, kidney failure as a result of PKD takes years to occur, resulting in a need for dialysis or kidney transplant.