CPAM type 3
Thursday 5 April 2012
CPAM, type 3, the small cystic or solid type, occurs infrequently (5% of cases), is seen exclusively in the ﬁrst days to month of life, has a notable male predominance, and owing to its large size and association with maternal polyhydram-nios and fetal anasarca, has a high mortality rate.
Increased maternal levels of serum alpha-fetoprotein have been noted in the second trimester of two cases of type 3 CPAM.
CPAM, type 3, the original lesion described by Ch’in and Tang, consists of a large, bulky, parenchymal mass involving an entire lobe or even an entire lung.
The mass effect of the lesion consistently produces mediastinal shift and often results in hypoplasia of the uninvolved lung.
Cysts are rarely larger than 0.2 cm in diameter, with the exception of scattered, larger, bronchiole-like structures.
Microscopically, the lesion resembles an immature lung devoid of bronchi.
Irregular, stellate-shaped, bronchiole-like structures lined with cuboidal epithelial cells are surrounded by alveolar ductules and saccules that are also lined by cuboidal cells, imparting the “adenomatoid” appearance for which this lesion was originally named.
Mucous cells, cartilage, and rhabdomyomatous cells are not present, and there is a paucity of vessels within the lesion.