Some symptoms of a complex kidney cyst include abdominal and flank pain, a palpable growth and hematuria. These symptoms may manifest when a complex renal cyst arises from a simple kidney cyst due to complications or enlargement, notes the Journal of the American Society of Nephrology.
Complex kidney cysts form when simple cysts become symptomatic. This occurs when simple cysts burst open and hemorrhage, become infected or grow large enough to put pressure on the other organs that sit adjacent to the kidneys. Cystic complication by hemorrhage is usually attributed to trauma, abnormal growth or bleeding diathesis. A renal abscess, which can result from an infected simple cyst, may acquire the features of a complex kidney cyst.
Patients who develop symptomatic cysts may experience physical discomfort in the area between the hip and ribs, an abnormally high temperature and the need to constantly urinate, states Cleveland Clinic. Blood may also be present in the urine, although minute quantities may not be noticeable.
Complex kidney cysts are characterized by the presence of calcification, multi-lobularity and demarcation abnormalities. This type of renal masses have a 13 to 90 percent likelihood of being malignant outgrowths, states the Kidney Cancer Institute. These renal tumors trigger symptoms by constricting, stretching or attacking regions surrounding the kidney. Depending on the location of the cyst, kidney function may also become impaired and lead to hypertension.