Congenital cystic adenomatoid malformation
(CCAM) of the lung is a rare but potentially life-threatening pulmonary
anomaly.
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CCAM can present at
different ages and in various clinical presentations. There can even be
asymptomatic patients who receive their diagnosis during the prenatal
period. The possibility of an underlying CCAM should be considered in
infants with recurrent chest infections or persistent abnormalities on
chest X-ray following an acute infection.
CCAM should also be
considered in cases with lung abscess, even in adolescents with no past
history of pulmonary complaints.
This congenital malformation features
abnormal air-spaces lined by cuboidal and columnar epithelium reminiscent
of the lining of bronchi and bronchioles.
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The air-spaces range from a complex of a
few large cysts to innumerable tiny spaces resembling developing lung.
Small amounts of cartilage and groups of goblet cells may be seen in
association with large cysts.
The cystic
adenomatoid malformation of the lung is an hamartomatous lesion , easily
identifiable by its morphology through the application of Stocker's et al
(1977) classification (type 1, 2 and 3) and also following the criteria of
Yousem, to understand the five types dependent on the level of
malformation in the airway and lung.
Presentation is usually in infancy with
respiratory distress or recurrent chest infections but cases detected in
adult life are described.
Surgical resection is the standard
treatment in a disease that is almost always unilateral and unilobar.
The mucus cell hyperplasia seen in the type
I malformation may provide the substrate for the subsequent development of
carcinomas.
The type II lesion is associated with
other congenital malformations such as renal dysgenesis and diaphragmatic
herniae.
The differential diagnosis of type I lesion
includes intralobar sequestration, bronchogenic cyst and bronchial atresia
while lesions with smaller cysts have to be distinguished from congenital
lymphangiectasia, interstitial emphysema and congenital lobar emphysema.
Cystic adenomatoid
malformation of the lung in an adult.
Minerva Chir.
1997 Apr;52(4):469-73
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.
This paper presents a case of CCAM in a 62-year-old male, who
presented with recurrent bacterial pneumonias and breathlessness one
exertion. The chest X-rays and CT scan revealed a patchy opacity in
the right lower pulmonary zone. Bronchoscopic examination was normal.
At surgery, a mass involving the right lower and middle lobes, and
enlargement of hilar lymph nodes were found. A bilobectomy was
performed without complications. Examination of the gross specimen
showed a lesion characterised by multiple small cysts, all less than 1
cm in diameter; they were lined predominately by columnar epithelium,
occasionally by ciliated epithelium. Rare cysts were lined by foreign
body giant cells. Elastic fibers and smooth muscle were present within
the cysts wall. Peripherally, there were normal alveoli and bronchioli
mixed with cysts, and plasmalymphocytic infiltrates. The final
diagnosis was Stocker's Type II CCAM of the lung. CCAM of the lung is
a rare development lesion of the lung and it has no sexual
predilection. It is usually unilateral and sublobar or lobar in size,
but occasionally it can be multilobar. 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. Based on
the size of the cysts, CCAM may be classified into three different
types: type I characterised 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, as that one in our report. The insult probably occurs
between 4th and 7th week of fetal life. The etiologic agent is
unknown. 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 recognise, as happened in our case. From the clinical
point of view, most of the lesions cause severe respiratory failure;
in adult individuals the diagnosis is difficult, since there are very
few relevant symptoms and signs. The patients can present with fever,
recurrent infections, breathlessness and haemoptysis. The chest X-rays
abnormalities are not specific and include homogeneous or multicystic
opacities. Similarly, other diagnostic methods add no further useful
informations. Surgical treatment is necessary also in adult patients,
because of the risk of recurrent pulmonary infections and malignancies
associated with CCAM. Lobectomy is the treatment of choice, but
sometimes a larger resection is required, when the lesion involves
more than one lobe.
