Kidney cysts are fluid-filled sacs that form in or on the kidneys. While most are simple cysts and usually harmless, causing no symptoms or damage, some can grow large, become infected, or affect kidney function. They’re often discovered during imaging tests for other issues. In rare cases, Kidney Cysts may be linked to more serious conditions like polycystic kidney disease (PKD). Treatment depends on the type, size, and symptoms—ranging from regular monitoring to surgical drainage in more complex cases.