Is S-shaped kidney always a fusion anomaly? Radiological diagnosis of a new anatomical variant of a single kidney

The term ‘S-shaped kidney’ typically refers to a variant of crossed-fused ectopia in which the crossed kidney is fused with the lower pole of the orthotopic kidney maintaining its orientation resulting in medially facing upper-pelvis and laterally facing lower-one; no kidney is present in the other renal fossa.[1] We present rational diagnosis and management of a rare anatomic variant of a single kidney with S shaped anomaly.