Twenty-eight cases of pulmonary cystic diseasas proved surgically and pathologically were studi ed roentgenologically

of which 21 were congenital and 7 acquired.Their roentgenograp-hic appearances included: 1. solitary air-containing cavity over 4-6 cm in diameter (n=7)

2. multiple aircontaining cavities of varying sizes(n=3)

3. siungle cyst containg fluid

manifested as round or oval homogeneous solid shadows (n=4)

4. single or multiple cavities containing both air and fluid with fluid levels (n=6)

5. pulmonary sequestration (n=8)

6 being in the left lower lobes and 2 in right lower lobes. The roentgenognaphic differential diagnosis and the mechanism of the cystic formation were discussed