ARRS 2022 Abstracts

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E1938. Congenital Pulmonary Airway Malformation: An Update
Authors
  1. Som Biswas; Le Bonheur Hospital, UTHSC
  2. Vijetha Maller; Le Bonheur Hospital, UTHSC
  3. Harris Cohen; Le Bonheur Hospital, UTHSC
Background
Congenital pulmonary airway malformation (CPAM), previously known as congenital cystic adenomatoid malformation (CCAM) is rare but the most common congenital lung lesion. Increasing and widespread use of antenatal ultrasound examination has resulted in an increase in the prenatal diagnosis of CPAM. Neonates may present with respiratory distress or may remain asymptomatic until later in life. Surgical resection is the definitive treatment. The occurrence of CPAM is mostly sporadic (types 1, 2, and 3) except for type 4, which has a potential for DICER 1 mutation.

Educational Goals / Teaching Points
This exhibit will discuss the type of congenital pulmonary airway malformation (CPAM); illustrate the imaging of the three types of CPAM on CT; describe hybrid lesions, which are usually type 2 CPAM with sequestration; and describe type 4 CPAM and potential association with pleuropulmonary blastoma and DICER 1 mutation.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
CPAMs are hamartomatous lesions that are comprised of cystic and adenomatous elements arising from tracheal, bronchial, bronchiolar, or alveolar tissue. Although connections with the tracheobronchial tree are noted, the connecting bronchi are usually not normal. The arterial supply and venous drainage from the lesion are almost always from the pulmonary circulation, though vascular connections to the systemic circulation have been noted in hybrid lesions. On radiographs and CT imaging, CPAMs are divided into large cyst (type 1, > 2 cm, most common), small cyst (type 2, < 2cm), and solid (microcystic, type 3), lesions. Type 4 CPAM, which has a distal acinar origin with no connection to bronchial or bronchiolar structures, is indistinguishable from type 1 CPAM on imaging. Type 4 CPAM is histologically like cystic pleuropulmonary blastoma (which can be seen as part of the DICER1 syndrome, autosomal dominant tumor predisposition syndrome).

Conclusion
All infants with a prenatal diagnosis of CPAM should have a chest radiograph in the neonatal period, even if they are asymptomatic and the lesion appeared to resolve on serial prenatal ultrasounds. As a part of preoperative planning, CT scan or MRI should be performed for characterization of the lesion. Family history should be explored in detail for cancers and cystic lesions that might suggest familial pleuropulmonary blastoma (PPB) syndrome and DICER 1 mutation.