대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

CCAM type I (Congenital Cystic Adenomatoid Malformation type I)

Radiologic Findings

Chest radiograph taken on Dec. 2002 shows increased mass-like opacity within air fluid level in the left lower lobe. Follow up radiograph after 2 years, there is persistent round mass-like opacity in the left lower lobe. CT scan shows well defined cystic lesions with multiple septae in the left lower lobe.

The left lower lobectomy was done. On gross specimen, an ill-defined irregular multi-septated cystic lesion (6.5x4.5x4cm) is present. It is apart from the bronchial resection margin. The internal surface of the cyst is graysh tan and fibrotic.

On the microphotograph (H&E stain x1000), bronchiole-like multiple cystic structures lined with columnar epithelium (black arrows) surrounded by smooth muscle tissue are shown.

Brief Review

Congenital cystic adenomatoid malformation of the lung (CCAM) is characterized by an adenomatoid proliferation of bronchiole-like structures and cysts formation. The condition is most commonly found in newborns and children and it may be associated with other malformations; rarely, the presentation is delayed until adulthood, so it should be considered in the presence of recurrent lung infections.

Typical histologic feature of CCAM are adenomatoid proliferation of bronchiole-like structures and macro- or microcysts lined by columnar or cuboidal epithelium and absence of cartilage and bronchial glands. Inflammatory changes are not found in infants, but may be present in adult patients result from recurrent infection.

Based on the size of the cysts, CCAM may be classified into three different types: type I characterized by multiple cysts over than 1 cm in diameter; type II with smaller cysts less than 1 cm in diameter; type III that shows solid lesions composed of bronchiole-like structures. Type II is commonly found in childhood, but is occasionally seen in adult patients. Though the etiologic agent is unknown, the insult probably occurs between 4th and 7th week of fetal life. The histologic diagnosis of CCAM is difficult in adult patient, perhaps because of supervening infections that sometimes distort the underlying diagnostic pathologic appearances and make them difficult to recognize.

Hemopneumothorax, pyopneumothorax and recurrent pneumothorax have been described in association with CCAM. Some malignant tumor such as bronchioloalveolar carcinoma, blastoma and sarcoma can be arising from the CCAM.

CT scans show the variable findings of CCAM; one of the most findings are areas with small cysts (90%), <2cm in diameter, and large (86%) cysts and areas of consolidation (43%) with heterogeneous attenuation and areas of low attenuation around cystic lesions (29%). Cysts that CT showed to be filled with air, fluid, or both correlated completely with the pathologic findings. Areas of consolidation corresponded histological to areas of glandular or bronchiolar structures with or without areas of endogenous lipoid or organizing pneumonia or mucus plugs. Areas of low attenuation corresponded to areas of microcysts blended with normal lung parenchyma.

Surgical resection is treatment of choice in adult patients, because of the risk of recurrent pulmonary infections, malignant transformation and pleural complication mentioned above. Lobectomy is the treatment of choice, but sometimes a larger resection is required, when the lesion involves more than one lobe.

References

1. Stocker JT, Madewell JE, Drake RM. Congenital cystic adenomatoid malformation of the lung. Classification and morphologic spectrum.

Hum Pathol. 1977;8:155-171.

2. Kim WS, Lee KS, Kim IO, Suh YL, Im JG, Yeon KM, Chi JG, Han BKK, Han MC. Congenital cystic adenomatoid malformation of the

lung: CT-pathologic correlation. AJR;1997:168:47-53.

3. Granata C, Gambini C, Balducci T, Toma P, Michelazzi A, Conte M, Jasonni V. Bronchioloalveolar carcinoma arising in congenital

cystic adenomatoid malformation in a child: a case report and review on malignancies originating in congenital cystic adenomatoid

malformation. Pediatr Pulmonol 1998;25:62-66.

4. Rosado-de-Christenson ML, Stocker JT. Congenital cystic adenomatoid malformation. Radiographics 1991;11:865-886.

5. Ueda K, Gruppo R, Unger F, Martin L, Bove K. Rhabdomyosarcoma of lung arising in congenital cystic adenomatoid malformation.

Cancer. 1977;40:383-388.

Keywords

Lung, Congenital,