00:01
So, clinical recognition of
pulmonary fibrosis,
just to rehash on that, it's several weeks
or months of exertion of dyspnoea usually
progressive getting worse over time. And the
presence of fine bibasal inspiratory crackles,
what we described as velcro crepitations,
plus restrictive lung function and a reduced
transfer factor. Those are the three characteristics
which identify clinically the patient who
is likely to have ILD. And they may or may
not have an underlying cause.
00:31
The main differential diagnosis for patients
presenting with pulmonary fibrosis is other
interstitial lung diseases such as sarcoidosis
and hypersensitivity pneumonitis. COPD, in
which case, there will be a smoking history,
although ILD patients often have smoking history,
anyway, but there are no crepitations in patients
with COPD. And then congestive cardiac failure,
but there should be some signs of abnormal heart
function and they should have a background
which might suggest that the heart is impaired,
such as hypertension, diabetes, previous ischemic
heart disease. So the CT scan is fundamental
for making the
diagnosis. The three dimensional ability of
the scan to identify infiltrates in the lung
parenchyma is vital to make the diagnosis,
and also for telling you what the likely pathology
and the likely potential cause there might
be for this ILD. So for example, in this slide,
we have two CT scans. The top one shows the
usual interstitial pneumonitis pattern which
is the crispy fibrosis with lots of collagen
and fibroblastic infiltration into the lung
which has a poorer prognosis and responds
less well to treatment. And that shows quite
a lot of subreticular intralobular changes and
you tend to get honeycombing, which is formation
of cyst within the lung in a subpleural and
a basal distribution.
01:57
The bottom CT scan shows the NSIP pattern
which is the more inflammatory pattern where
ground glass infiltrates are more dominant. With
fibrosis, you also get what we call traction
bronchiectasis where the scarring of the lung
tissue causes the bronchi to be pulled apart.
The important point here is that the CT scan will define
the distribution, and the type of infiltration
in the lung give you some indication of histology
for patients presenting a pulmonary fibrosis,
and help distinguish pulmonary fibrosis from
other causes of ILDs such as sarcoidosis and
hypersensitivity pneumonitis.