renal cysts – simple

differential diagnosis

multicystic kidney disease usually consists of many cysts of varying size and may be bilateral, unilateral or segmental. the segmental form is usually unilateral and multilocular”, less commonly a single large cyst can also form. upj obstruction usually presents with a dilated renal pelvis or caliectasis. multiple nonspherical cystic lesions radiating from the renal pelvis can often be seen but occasionally a single large cyst can form replacing the renal pelvis. adult polycystic kidney disease can rarely present in a fetus as a small single cyst but with time, progressively more cysts form and the kidneys assume an enlarged solid appearance similar to ipkd. a perinephric (or paranephric) urinoma adjacent to the renal capsule may appear to be a cortical cyst but it usually has a more elliptical shape. mesoblastic nephromas and wilmsí tumours are usually solid but can become necrotic with areas of cystic degeneration present. identification of solid areas of tumour rule out simple cyst(s). also, polyhydramnios is frequently associated with mesoblastic nephroma. rarely, a fetus with severe thrombocytopenia can develop a spontaneous renal haematoma resulting in a cystic lesion. other areas of haemorrhage may be identified or the diagnosis suspected based on history.”