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Antenatal ultrasound diagnoses many congenital lung malformations,
but we now have to decide what to do for a baby affected by an abnormality
that may previously have escaped detection. Initial reports described
a poor outcome for fetuses with lung masses detected in the second
trimester. It is now clear that many lung lesions disappear or regress
considerably by term, and the outcome for such fetuses is in general
very good. Postnatal regression of lung malformations has also been
described. The dilemma in the postnatal period is whether to opt
for observation or surgery.
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The nomenclature of congenital lung disease may be confusing.
For example, sequestration and cystic adenomatoid malformation (CCAM), sometimes
assumed to be separate identities, but histologic features of both
may be found within the same lesion. There is inconsistent use of
nomenclature before and after birth. It is necessary to think in
new ways about congenital lung disease. The following principles
should be followed1:
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1. What is actually seen should be
described, without embryologic or pathologic speculation, which
may later be proved wrong. The same clinical appearance (eg, a multicystic
mass) may have one of several different histologic appearances when
excised. A simple “catch-all” term, congenital
thoracic malformation (CTM), is useful for clinical discussions,
prior to any pathologic examination.
2. The description should be in everyday language, avoiding ambiguity. For
example, hypoplastic lung could mean a lung that is small but otherwise
normal, or small and structurally abnormal; congenital small lung (CSL)
is clearer, and avoids assumptions about structure. Congenital lobar “emphysema” is
another source of confusion as in adults it implies lung destruction.
What is actually seen is a congenital large hyperlucent lobe (CLHL).
Throughout this chapter, established terms will be given in brackets
after the proposed new term. A summary comparison of old and new
nomenclature is given in Table 507-1,
and relevant investigations summarized in Table
507-2.
3. The respiratory system should be described systematically.
The lung is formed from 6 “trees”: bronchial,
systemic and pulmonary arterial, systemic and pulmonary venous,
and lymphatic. There are no known abnormalities of bronchial venous
drainage, so in practice, only five trees need to be considered.
4. Important associated organs (in particular, the heart, great
vessels, chest wall, and abdominal contents) should be considered
in a systematic manner. Congenital multisystem diseases may affect the
lung.
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