Epidemiology

 25% of all congenital lung lesions
 4-26% of cases can be associated with other congenital abnormalities.
 estimated incidence: 1 case per 25,000-35,000 pregnancies.

Subtypes

 CPAM type O - CCAM type O (acinar dysplasia)
 CPAM type 1 - CCAM type 1 (bronchial/bronchiolar)
 CPAM type 2 - CCAM type 2 (bronchiolar)
 CPAM type 3 - CCAM type 3 (bronchiolar/alveolar duct)
 CPAM type 4 - CCAM type 4 (peripheral)
 CPAM type 5 - CCAM type 5

CCAM type 0 (congenital acinar dysplasia, congenital acinar aplasia) (1-3%) (neonates, other malformations, poor prognosis)

 solid appearance
 small and firm lungs
 bronchial-type airways with cartilage, smooth muscle and glands separated by abundant mesenchymal tissue

CCAM type 1 (60-70%) (bronchial) (neonates and infants, resectable, good prognosis, possible carcinomatous change)

 1 or more large cysts measuring 2-10 cm in diameter. Larger cysts are often accompanied by smaller cysts, and their walls contain muscle, elastic, or fibrous tissue.
 cartilaginous plates (12%) (12883247)
 Cysts are 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)

CCAM type 2 (10-15%) (bronchial/bronchiolar) (neonates, other malformation, poor prognosis)

 sponge-like appearance
 multiple small cysts (0.5 to 2 cm)
 small relatively uniform cysts resembling bronchioles separated by normal alveoli
 cysts are lined by cuboid-to-columnar epithelium and have a thin fibromuscular wall.
 solid pale tumor-like tissue
 striated muscle in 5%

CCAM type 3 (5%) (bronchiolar) (neonates, poor prognosis)

 solid appearance
 excess of bronchiolar structure separated by small air spaces, with cuboidal lining, resembling late fetal lung
 grossly a solid mass without obvious cyst formation
 microscopic adenomatoid cysts

CCAM type 4 (28%) (peripheral) (neonates and infants, good prognosis)

 large cysts (up to 10 cm)
 cysts lined by a flattened epithelium (type 1 and 2 pneumocytes) resting on loose mesenchymal tissue
 focal stromal hypercellularity (50%) (12883247)
 focal immature cartilage (12883247)
 associated pleuropulmonary blastoma (bilateral type 4 CCAM with stromal cellularity) (14%) (12883247)

Associations

 pulmonary malformations

• extralobar sequestration (CCAM type 2 and CCAM type 3) with systemic arterial supply
• controlateral extralobar pulmonary sequestration (15300558)
• bronchial atresia (7298053)
• polyalveolar lobe

 epithelial hyperplasias

• atypical goblet cell hyperplasia
• nonmucinous atypical adenomatous hyperplasia
• focal mucous cell hyperplasia (25% of type 1 CCAM)

 renal malformations

• cystic renal disease
• ipsilateral multicystic renal dysplasia (15630540)
• bilateral renal agenesis
• contralateral renal agenesis (15630540)

 ovarian germ cell hypoplasia (15630540)

 malignant tumors

• pleuropulmonary blastoma (bilateral type 4 CCAM with stromal cellularity) (14%) (12883247)
• rhabdomyosarcoma (16007610, 11431779, 9314270)
• malignant mesenchyma
• bronchioloalveolar carcinoma (31% of type 1 CCAM) (12883247, 9475333)
• atypical goblet cell hyperplasia ((15138930)

 chromosomal anomalies

• trisomy 13 (12673637)
• trisomy 18 (11173951)
• chromosme 18 rearrangement (partial deletion of 18p and partial duplication of 18q) (11173951)

 miscellaneous

• aneurysm of the vein of Galen (15022074)
• sirenomelia
• intestinal atresia
• skeletal malformations
• cleft palate
• hydranencephaly
• hydrocephalus
• diaphragmatic hernia

Diferential diagnosis

 stromal cellularity in a type 4 CCAM should raise the possibility of blastomatous transformation.

See also: congenital pulmonary cysts

References

 Vargas SO, Korpershoek E, Kozakewich HP, de Krijger RR, Fletcher JA, Perez-Atayde AR. Cytogenetic and p53 profiles in congenital cystic adenomatoid malformation: insights into its relationship with pleuropulmonary blastoma. Pediatr Dev Pathol. 2006 May-Jun;9(3):190-5. PMID: 16944975

 Wilson RD, Hedrick HL, Liechty KW, Flake AW, Johnson MP, Bebbington M, Adzick NS. Cystic adenomatoid malformation of the lung: Review of genetics, prenatal diagnosis, and in utero treatment. Am J Med Genet A. 2006 Jan 15;140(2):151-5. PMID: 16353256

 Pai S, Eng HL, Lee SY, Hsiao CC, Huang WT, Huang SC. Rhabdomyosarcoma arising within congenital cystic adenomatoid malformation. Pediatr Blood Cancer. 2005 Nov;45(6):841-5. PMID: 16007610

 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

 Stocker JT, Madewell JE, Drake RM. Congenital cystic adenomatoid malformation of the lung. Classification and morphologic spectrum. Hum Pathol. 1977 Mar;8(2):155-71. PMID: 856714

 Cha I, Adzick NS, Harrison MR, Finkbeiner WE. Fetal congenital cystic adenomatoid malformations of the lung: a clinicopathologic study of eleven cases. Am J Surg Pathol. 1997 May;21(5):537-44. PMID: 9158677

 Cangiarella J, Greco MA, Askin F, et al. Congenital cystic adenomatoid malformation of the lung: insights into the pathogenesis utilizing quantitative analysis of vascular marker CD34 (QBEND-10) and cell proliferation marker MIB-1. Mod Pathol 1995; 8:913-8.