Simple Renal Cyst: This is the most common cause of renal cyst pain. Simple renal cysts are benign fluid-filled structures that can cause pain due to their size, location, or if they become infected or hemorrhagic.

Polycystic Kidney Disease (PKD): An inherited disorder characterized by the growth of numerous cysts filled with fluid in the kidneys, which can cause pain due to cyst rupture, hemorrhage, or nephrolithiasis.
Renal Cell Carcinoma: Although less common, renal cell carcinoma can present with a cystic component and cause pain due to the tumor's size or metastasis.
Pyelonephritis or Kidney Infection: Infection of the kidney can cause pain and may be associated with renal cysts, especially if the cyst becomes infected.

Ruptured Renal Cyst: A ruptured cyst can lead to severe, acute pain and potentially life-threatening hemorrhage, making prompt diagnosis crucial.
Nephrolithiasis (Kidney Stones): While not directly related to cysts, kidney stones can cause severe pain and are a common condition that must be considered in the differential diagnosis of renal pain.
Renal Infarction: This is a rare but potentially life-threatening condition where the blood supply to the kidney is interrupted, which could be related to or mimicked by complications of renal cysts.

Multicystic Dysplastic Kidney: A rare congenital anomaly where the kidney is replaced by multiple cysts, which can cause pain and is usually diagnosed in childhood.
Medullary Cystic Disease: A rare inherited disorder characterized by the development of cysts at the boundary between the renal medulla and cortex, leading to chronic kidney disease and potentially pain.
Acquired Cystic Kidney Disease (ACKD): Associated with long-term kidney disease, especially in patients on dialysis, ACKD can increase the risk of renal cell carcinoma and cause pain due to cyst hemorrhage or other complications.