Criteria

Type 1

Thick outer wall (at least 0.5 mm)

Thick internal septa (at least 0.5 mm)

Type 2

One or more intracystic masses

Masses are peripheral, nodular

Type 3

Mixed cystic and solid components

Predominantly (at least 50%) cystic

Type 4

Mixed cystic and solid components

Predominantly (at least 50%) solid

May include eccentric cystic components