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Lung-nontumor

Cystic disease/congenital anomalies

Cystic adenomatoid malformation


Reviewers: Elliot Weisenberg, M.D. (see Reviewers page)
Revised: 22 December 2011, last major update August 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Definition
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● Rare hamartomatous disorder of variably sized cysts; 1 per 25,000 births
● Also called congenital pulmonary airway malformation because not all lesions are cystic or adenomatoid

Clinical features
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● Associated with stillbirth, neonatal distress and bronchial atresia
● May develop with and be related to other congenital or acquired lung conditions (Arch Pathol Lab Med 2002;126:934)
● May regress spontaneously

Classification
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Type 0: 1-3%, small/firm lungs, formerly called acinar dysplasia; associated with other malformations; incompatible with life (Pediatr Crit Care Med 2007;8:580)
Type I: 60-70%, large cysts up to 10 cm lined by pseudostratified ciliated cells interspersed with mucus cells; may appear in older children and adults; good prognosis since can resect; cartilage inconspicuous to absent; shows lepidic growth within cysts and adjacent lung, resembling bronchioalveolar carcinoma
Type II: 10-15%, small cysts up to 2 cm, resemble dilated bronchioles separated by normal alveoli; very little if any cartilage; rare, if any mucus cells; associated with other malformations; poor prognosis
Type III: 5%, solid gross appearance, excess bronchiolar structures separated by small air spaces with cuboidal epithelium resembling fetal lung; usually occupies entire lobe, may involve multiple lobes, unilateral or bilateral, left lower lobe most commonly involved; poor prognosis
Type IV: 15%, large cysts up to 10 cm lined by flattened epithelium; good prognosis; similar to grade 1 pleuropulmonary blastoma although less cellular; sample generously to rule out blastoma

Case reports
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● Term newborn with abnormal fetal ultrasound and MRI (Case of the Week #58)

Treatment
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● Close followup of asymptomatic infants with elective surgery for persistent lesions within first year of life (Arch Dis Child Fetal Neonatal Ed 2006;91:F26, Int J Gynaecol Obstet 2005;89:99)

Gross images
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Type I

   
Type II


Type III


Type IV

Micro description
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● Variably sized cysts lined by “adenomatoid”, columnar-type epithelium

Micro images
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Type I

       

       
Type II


Type III

Molecular description
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● No karyotypic abnormalities; no p53 mutations (Pediatr Dev Pathol 2006;9:190)

Additional references
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Am J Surg Pathol 2003;27:1139

End of Lung-nontumor > Cystic disease/congenital anomalies > Cystic adenomatoid malformation


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