Congenital Cystic Adenomatoid Malformation (CCAM) of the Lung Dr Bental – NICU – Laniado Hospital בס " ד

Congenital cystic adenomatoid malformation (CCAM) of the lungs is a developmental abnormality (hamartoma) arising at ~ the seventh week of gestation from overgrowth of the terminal respiratory bronchioles modified by intercommunicating cysts (Stocker et al. 1977).Occurrence is sporadic unrelated to race, maternal age, or familial genetic history.Stocker et al. 1977

In the fetus CCAM presents in association with hydramnios, hydrops, prematurity, and stillbirth.

Etiology/Pathophysiology Congenital hamartomatous lesion of the lung

Pathology

Cystic Adenomatoid MalformationLower lobe of lung.Black arrow points to large cyst; yellow areas to smaller cysts.White arrows highlight pleural surface.Portion of lung adjacent to pleura has normal apearance; remainder shows enlarged spaces.

Pathology There are 3 subtypes, all of which lack normal bronchial communications: Type I - multiple large air or fluid filled cysts, usually greater than 2.0 cm in diameter.

AP and lateral chest radiographs show a well defined cystic mass in the left lung. Type 1.

PA chest radiograph shows a cystic mass in the left upper lobe Lung windows from an unenhanced CT scan of the chest in the same patient better demonstrate the cystic nature of the left lung mass. Type 1

Type II - variably sized less bulky lesion with smaller cysts.

Type III - bulky mass composed of multiple tiny, microscopic cysts resembling bronchi that involves the entire lobe. Adenomatous hyperplasia with an increase in terminal bronchiolar structures, as well as a polypoid arrangement of mucosal epithelium is seen.

Autopsy gross photograph showing the abnormally enlarged left lung containing multiple, small cysts.

Bilateral CCAM

Differential Diagnosis Congenital lobar emphysema Bronchogenic cyst Bronchopulmonary sequestration Prior infection with pneumatocele formation Diaphragmatic hernia

Congenital Lobar Emphysema (CLE) Supine chest radiograph showing a large cystic lucency in the left upper lobe.

ANTENATAL DIAGNOSIS Type I CCAM appears as large cystic spaces usually in the upper or middle lung. Type II appears as multiple small cysts < 1 cm on a slightly echogenic background. Type III appears as an echogenic mass with no cystic structure visible.

US of the fetus showing a large mass in the thorax

ANTENATAL DIAGNOSIS Polyhydramnios- Due to esophageal compression (Donn et al., 1981), or increased fetal lung fluid production by the abnormal tissue (Krous et al., 1980)Donn et al., 1981Krous et al., 1980 Fetal hydrops -From venocaval obstruction and cardiac compression secondary to mediastinal shift) Ascites

US showing integumentary edema and ascites

FETAL THERAPY Following a targeted ultrasound amniocentesis and cardiac echo are recommended to evaluate the fetus for additional anomalies Prenatal MRI (?).

FETAL THERAPY HYDROPIC FETUS In the hydropic fetus with an isolated lesion prior to 32 weeks' thoracoamniotic shunting is particularly useful for alleviating mediastinal compression in predominantly cystic CAM (Nicolaides K and Azar GB, 1990, Thorpe-Beeston JG 1994).Nicolaides K and Azar GB, 1990,Thorpe-Beeston JG 1994

FETAL THERAPY In cases not amenable to drainage (multiple small cysts or Type III) referral for fetal lobectomy should be considered. The hydropic fetus > 32 weeks' is better served by ex utero lobectomy(Adzick NS, 1993).Adzick NS, 1993 The major complications associated with surgical interventions are premature labor and preterm rupture of membranes

FETAL THERAPY NONHYDROPIC FETUS The nonhydropic fetus with isolated CCAM occupying < 50% of the thorax appear to do reasonably well and may be followed with serial exams (Dommergues M et al 1997).Dommergues M et al 1997).

Postnatal Clinical Presentation The most common presentation is acute respiratory distress in the newborn in the first few hours of life. Alternatively, it can present at several months or several years of age as recurrent pneumonias.

Supine chest radiograph at one hour of life shows a solid mass in the left hemithorax causing mediastinal shift to the right, evidenced by the position of the endotracheal tube.

Supine chest radiograph at three hours of life in the same patient shows a multiseptated cystic mass in the left hemithorax causing mediastinal shift to the right.

The chest-computerized tomograph demonstrates a right lower lobe congenital cystic adenomatoid malformation (CCAM) in a 6-week-old infant who presented with tachypnea. The most striking feature is the solitary enlarged cyst surrounded by a number of microcysts. This lesion was resected without complication

POSTNATAL MANAGEMENT A significant number of CCAMs either decrease in size or resolve in utero spontaneously (Bromley B et al 1995 ).Bromley B et al 1995 However, Winters et al have demonstrated persistent abnormalities after birth in cases of "disappearing" fetal lung masses.

POSTNATAL MANAGEMENT CT scan in the postnatal period is therefore recommended as the findings are often subtle on radiograph(Winters et al.,1997).Winters et al.,1997) Frequent infectious complications and malignant change in CCAM argue for resection of these tumors. (Granata et al,1998, Kaslovsky RA et al 1997, d'Agostino S et al 1997, Ribet ME et al 1995)Granata et al,1998,Kaslovsky RA et al 1997d'Agostino S et al 1997