CPAM type 1
Friday 17 June 2005
CCAM type 1 (60-70%) (bronchial) (neonates and infants, resectable, good prognosis, possible carcinomatous change)
CPAM, type 1, the large or predominant cyst type, presents primarily within the ﬁrst week to month of life but can be seen in older children and even young adults.
CPAM, type 1 accounts for nearly 65% of cases and is usually readily amenable to surgery with a good prognosis.
Grossly, the type 1 lesion is characterized by single or multiple large cysts (3 to 10 cm in diameter) surrounded by smaller cysts and compressed normal parenchyma.
Microscopically, the larger cysts are lined with ciliated, pseudostratiﬁed columnar epithelium and the smaller ones by cuboidal to columnar epithelium.
More than 45% of the cases display segments of mucus-producing cells among the epithelial lining of the larger cysts or in bronchioles and alveolar duct–like structures adjacent to the larger cysts.
These mucous cells have similar characteristics to those of pyloric mucosa.
Wang et al. suggest that these mucous cells may have the potential for malignant transformation to bronchioloalveolar carcinoma.
Several reports of the occurrence of CPAM and bronchioloalveolar carcinoma have been published, and a convincing argument can be made in establishing an association between the two diseases.
The walls of the CPAM, type 1 cysts are composed of elastic tissue overlying ﬁbromuscular connective tissue, and in 5% to 10% of cases, cartilage plates.
neonates and infants
possible carcinomatous change (bronchioloalveolar carcinoma)
1 or more large cysts measuring 2-10 cm in diameter
larger cysts are often accompanied by smaller cysts
cyst walls containing muscle, elastic, or fibrous tissue
cysts frequently lined by pseudostratified columnar epithelial cells often interspersed with rows of mucous cells
focal mucous cell hyperplasia (12 to 25% of type 1 CCAM)
microscopic foci of bronchioloalveolar carcinoma (1 to 31% of type 1 CCAM) (12883247)
MacSweeney F, Papagiannopoulos K, Goldstraw P, Sheppard MN, Corrin B, Nicholson AG. An assessment of the expanded classification of congenital cystic adenomatoid malformations and their relationship to malignant transformation. Am J Surg Pathol. 2003 Aug;27(8):1139-46. PMID: 12883247