Definition
A group of congenital malformations of the developing lung, which may be supplied by either or both of the pulmonary or systemic arterial system, and drain to pulmonary or systemic veins. The histology of the excised specimen may show many different cell and tissue types.
Causes
No known causes identified.
Clinical Presentations
Hitherto, CCAM and other congenital cystic malformations of the lung
(which I group together as congenital thoracic malformations, or CTMs
[1]) usually presented with symptoms such as recurrent infection, and
it was obvious that treatment was needed. Now they present in the pre-symptomatic
phase, and it is difficult to know how best to advise the parents.
In most cases, the baby is well after delivery.
Investigations
Serial monitoring antenatally with ultrasound scans. Postnatally, the
chest radiograph (CXR) is either normal, or reveals minor changes only.
The CT scan often shows a more extensive lesion than the CXR. The blood
supply to the CTM should be defined by contrast CT or magnetic resonance
imaging angiography.
Treatment
In the short term, the prognosis of antenatally diagnosed lesions is
very good; although at 20 weeks gestation the lesions may be large,
in many babies they regress considerably, and most survive to be born
at term. The Kings group have reported on 67 fetuses with an antenatally
diagnosed congenital lung [2]. Sixty four were born alive, and 42 underwent
postnatal surgery. Surgery was required in 45% of lesions showing late
gestation ‘resolution’. Although there was some correlation
between the antenatal appearances and the need for surgery, this was
not usefully predictive for an individual, and the need for operation
was judged on postnatal features. Specifically, hydrops and mediastinal
shift are not such bad prognostic features as was once thought.
Babies with a very large CTM, or one that is compressing the airway,
may present with respiratory distress in the newborn period, in which
case immediate surgery is likely to be required. If the baby is well,
are no data on which to base treatment decisions. It is not possible
to quote a risk of complications, because the denominator of the risk
equation (how many undiagnosed CTMs in the past have caused no problems)
is unknown. Possible complications include infection, pneumothorax, bleeding
from or into the CTM, malignant change, and high output hear failure
if the CTM is fed by a large systemic artery. Complications are rare
in early life, and many of the protagonists of surgery would usually
recommend resection of the lesion at about 2 years of age. Aa an alternative
to surgery, a CTM supplied by a large systemic vessel may be considered
for coil embolization, which may be the only therapy needed.
Others would advise an expectant approach, particularly with small CTMs.
If a CTM does become infected, then surgery is inevitable; antibiotics
can lead to temporary improvement, but recurrent infection is inevitable.
The risk of malignancy is less clear. Primary intrathoracic malignancy,
irrespective of the presence of a CTM, is rare. There are isolated case
reports of malignant tumours in children with a CTM. The risk attributable
to the malformation is not known. Metaplasia or pre-neoplastic change
is not a feature of excised CTMs [3]. Furthermore, malignant disease
may develop in sites distant from the original malformation [4], implying
that the malformation is merely a marker of increased malignant potential
throughout the lungs, in which case removing the malformation would not
deal with the underlying problem. It is suggested that a higher incidence
of suspicion is justified in those with bilateral disease, a family history
of pleuropulmonary blastoma, pulmonary cysts or renal anomalies, or a
close relative with a childhood malignancy, especially Wilm’s tumour
or medulloblastoma.
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Useful references:
1. Congenital lung disease: a plea for clear thinking
and clear nomenclature.
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Bush A.
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Pediatr Pulmonol 2001; 32: 328-337
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2. Current outcome of antenatally
diagnosed cystic lung disease.
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Davenport M, Warne SA, Cacciaguerra S, Patel S, Greenough
A, Nicolaides K.
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J Pediatr Surg 2004; 39: 549-56
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3. Pulmonary sequestration: a review of 26 cases.
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Halkic N, Cuenoud PF, Corthesy ME, Ksontini R, Boumghar
M.
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Eur J Cardiothorac Surg 1998; 14: 127-133
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4. Pleuropulmonary blastoma: is prophylactic resection
of congenital lung cysts effective? |
Papagiannopoulos KA, Sheppard M, Bush A, Goldstraw P. |
Ann Thorac Surg 2001; 72: 604-605 |
Web links:
Further information on the relationship between CCAM and pleuropulmonary
blastoma can be found at www.ppbregistry.org.
Clearly, more evidence about the natural history of untreated
CTM, and the risk of complications, is needed. Whether or not
the baby has surgery, it is essential that normal child care,
including immunizations, is carried out. There is an ongoing
natural history study which is attempting to answer some of these
questions prospectively, recruiting babies at the time of antenatal
ultrasound diagnosis. If you are interested in being part of
this study (LOTOS), further details can be obtained from the
principal investigator, Dr Lyn Chitty (l.chitty@ich.ucl.ac.uk
).
Download this text as a .PDF HERE
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