The effect of fenestration procedure on liver regeneration in a case of polycystic liver disease.

We encountered a case of polycystic liver disease for which unroofing and fenestration procedures were performed. The patient was a 55-year-old Japanese female with epigastralgia and abdominal fullness. On computed tomography, millions of low-density areas were seen, particularly in S6, 7, where huge cysts 15 cm in diameter were observed. Magnetic resonance imaging showed a T1 low T2 high-intensity lesion, which was compatible with simple cysts. Unroofing for the cysts in S6, 7 and fenestration of other cysts were performed. Histological examination revealed cuboidal and flat monolayer epithelia with no dysplasia in the wall of the cysts. The postoperative course was uneventful, and the patient's abdominal symptoms remarkably improved. The percentage of the liver volume which was increased in relation to standard liver volume was reduced from 241% (3386 mL: liver parenchyma 750 mL, cysts 2636 mL) to 180% (2525 mL, 1566 mL, 959 mL, respectively) after surgery. The potent mitogen, hepatocyte growth factor, was rapidly increased after the operation and stayed high during the observation period. In this patient, since no liver resection was performed, liver regenerative stimulus was considered to be the loss of space. This phenomenon represents a model of liver regeneration in response to loss of occupied space in an absence of shear stress.