The fragmented staghorn calculus: a radiological sign of pyonephrosis.

Staghorn calculi may cause several complications, particularly important being the development of pyonephrosis due to long-standing infection. We describe four patients who presented with either a marked systemic illness or a loin mass due to pyonephrosis. In each patient, the plain abdominal radiograph showed a fragmented staghorn calculus, which is suggested as a radiological sign of pyonephrosis and indicative of the need for surgical attention.