How, Where and When To Perform a Bronchial Biopsy? Clinical
Applications.
Petr Pohunek*, Katarína Urbanová*, Tamara Svobodová*, Jiří
Uhlík**, Ludmila Hornofová***
*Division
of Pediatric Pulmonology, Pediatric Department
**Department
***Department
of Histology and Embryology
of Pathology and Molecular Medicine
Charles University, 2nd Faculty of Medicine, University
Hospital Motol, Prague Czech Republic
Supported by the grant No. NT 11444 of the Internal Grant
Agency, Ministry of Health, Czech Republic, and the Research
Project MZ0FNM2005.
Corresponding author:
Prof. Petr Pohunek MD PhD FCCP
Pediatric Department, University Hospital Motol
V Úvalu 84
15006 Praha
Czech Republic
e-mail: petr.pohunek@LFMotol.cuni.cz
Introduction.
Sampling of tissue during bronchoscopy has been a long term
established method of obtaining information about pathological
lesions and processes in the bronchial mucosa. Main role of
this technique is in the diagnosis of malignant tumors in
adults. In children, bronchoscopic biopsy had been used much
less frequently as the indications of bronchoscopy are mostly
different to those in adults and tumors of the airways are
rather rare. However, understanding of the importance of
morphological description and confirmation of pathological
processes in the bronchial wall in children with chronic
bronchial pathologies has brought bronchial biopsy to an
attention.
Indications of bronchial biopsy.
Flexible bronchoscopy has now been widely used in the
diagnostics of respiratory pathologies in children of any age.
Assessment of airway patency, excluding of congenital
anomalies, stenoses and instability of the airways belong to
the most frequent indications. These are usually well
described using just visual investigation and anatomical
evaluation, while morphological evaluation using a mucosal
biopsy is not always necessary. Other indications comprise
chronic respiratory symptoms, such as persistent or frequently
recurrent pulmonary infiltrations, long-term coughing with or
without production of sputum, and wheezing. In these cases,
anatomical and visual evaluation is usually not sufficient and
other methods are required to describe and diagnose the
pathology more accurately. Among these usually the
bronchoalveolar lavage and mucosal biopsy are very helpful.
Targeted biopsy is extremely useful also in evaluation of
abnormal intrabronchial structures or masses.
Techniques of bronchial biopsy.
Brush biopsy
Brush biopsy is an endoscopic technique whose purpose is to
sample superficial cells from the pathological lesions or, in
diffuse disease, from the affected mucosa. It has been often
used in adults for a diagnosis of malignant lesions, in
children the indication is usually to sample material for
cytological analysis of inflammation, evaluation of infection
(e.g. tuberculosis) or to obtain viable cells for ciliary
studies. The technique differs according to the size of used
bronchoscope and its working channel. A standard
protected brush technique can be used with the bronchoscopes
with 2.2 mm channel. Thinner pediatric bronchoscopes (e.g. 3.6
and 2.9 mm scopes) are equipped with the 1.2 mm channel,
therefore, only unprotected thin brushes can be used. To
prevent losing of the sampled material during the withdrawal
of the brush through the channel, the unprotected brushing is
usually left as a last procedure during bronchoscopy and after
sampling the brush is only just withdrawn into the channel and
removed together with the bronchoscope. Then the brush can be
pushed out again to remove the sampled material for further
processing.
Endobronchial biopsy
Compared to brush biopsy, the aim of bronchial biopsy is to
obtain a small piece of tissue that contains all the relevant
structures and cells for appropriate histological analysis. In
localized pathologies, such as visible endobronchial lesions,
nodules or masses, the biopsy must be taken directly from the
visible lesion. This may be difficult mainly in lesions that
can be approached only with extensive flexion of the
instrument or in some mucosal lesions not sufficiently
protruding from the mucosa that require a tangential approach.
Another technical problem limiting the yield of bronchial
biopsy is the size of available forceps. This is not an issue
when using bronchoscopes with the 2.2 mm channel. For these
instruments, different types of reusable or single-use forceps
are available. The most widely used type of forceps for
pediatric bronchial biopsy is the fenestrated long oval cup
forceps that usually provides sufficiently large sample for an
appropriate histological evaluation.
More difficult is to obtain an appropriate bronchial biopsy in
smaller children while using a bronchoscope with the channel
of 1.2 mm in diameter. Only few models of such thin forceps
are available and due to their very small sizes, the bioptic
samples are often inadequate. Nevertheless, there is a growing
number of papers publishing the results of the analysis of
sufficient bronchial biopsies in small children what suggests
that with proper experience and technique and in a very good
co-operation with the histological laboratory, also these
small samples can be used for both diagnostic evaluation and
research.
The site for bronchial biopsy is derived from the expected
pathology and visual assessment. In visible localized
pathologies, the biopsy has to be taken directly from the
lesion. In general pathologies, the site of biopsy is usually
a properly accessible site with a possibility of a good grasp
by the forceps. This is mostly any of the interbronchial
carinas, where the positioning of the forceps and the
embedding into the mucosa is better that anywhere else. To
avoid distortion of the histological result by possible
secondary changes, it has been recommended to avoid sampling
from the main carina or from the origin of the right upper
lobe bronchus. It is always better to sample more specimens
(usually 3-4) to make sure that at least some will be adequate
for analysis.
Processing of the histological specimen.
The sequence of processing depends largely on the purpose of
the biopsy and expected staining and analysis. For simple
morphological analysis, the sampled tissue can be immediately
fixed in formaldehyde and transferred to the laboratory for
embedding, cutting and staining. For basic evaluation, the
standard hematoxylin-eosin staining is usually sufficient;
however, some targeted staining protocols can be used for more
detailed analysis. Among these, mainly stainings for collagen
and other matrix proteins or stainings emphasizing mucus
producing elements can be useful. For research analysis, the
immunohistochemistry has been frequently used, mainly for
analyzing cell populations of special interest or various
extracellular or intracellular proteins (tenascin,
fibronectin, metalloproteinases, growth factors). The material
intended for the immunohistochemical analysis should be fixed
by buffered paraformaldehyde rather than standard formaldehyde
and the fixation should not be prolonged (optimum 4 hours). In
special indications, such as ciliary structural studies, the
specimen can be processed for ultrastructural analysis using
electron microscopy. In this case, special protocols and
fixatives are used.
The yield of bronchial biopsy.
Bronchial biopsy is certainly an unique method for evaluation
of endobronchial masses and confirming or excluding possible
neoplasms. It may help in diagnosing other non-malignant
endobronchial pathologies, such as tuberculosis, sarcoidosis,
virus-induced lymphoproliferation, granulations etc.
In general non-malignant pathologies, most of the recent
studies using bronchial biopsies in children have focused upon
asthma and analysis of remodeling of bronchial wall in
children with asthma of different severity. These studies have
confirmed presence of eosinophilic inflammation, deposition of
matrix proteins and increased mass of bronchial smooth muscle
and vascularity (1 - Barbato). Some of these studies confirmed
presence of such changes even before the clinical diagnosis of
asthma or in children with only intermittent symptoms (2 Pohunek, 3-Barbato). From purely research approach, this has
been now more and more used also in clinical evaluation in
differential diagnosis of obstructive symptoms in children.
Presence of cellular infiltration and marked signs of
remodeling can support the diagnostic and therapeutic
decisions in children with atypical symptoms.
Inflammation and epithelial damage in the bronchial mucosa can
also be detected and assessed in other pathologies, such as
recurrent or chronic bronchitis. The quantitative histological
data compared with clinical results in a well designed study
showed extensive epithelial damage, shedding and edema in
children with recurrent bronchitis.(4) This histological
finding proved that children with recurrent bronchitis can
develop severe bronchial inflammation and have a reduced
epithelial integrity and depressed mucociliary function.
Safety of bronchial biopsy in children.
Safety concerns were apparently the main reason why routine
use of bronchial biopsy was slowly accepted as a possible
supplemental method in pediatric flexible bronchoscopy.
However, growing experience with this method in children
proves that correctly indicated and properly performed
endobronchial biopsy does not add any significant risk to that
inherent in the bronchoscopy itself. In a large safety study
by de Blic analyzing more than 1300 flexible bronchoscopies in
children, the authors encountered one pneumothorax associated
with endobronchial biopsy, which was not reported in another
rather large study that analyzed safety of 170 bronchial
biopsies in children aged 2.5 to 16 years with chronic
respiratory symptoms. In this study the authors did not report
any significant complication, such as pneumothorax, bleeding
or subsequent fever. The possibility of adverse effect of such
procedure should, however, be always on one´s mind. Especially
in situations with expected increased fragility and increased
vascularization, the risk of bleeding or bronchial perforation
might be theoretically higher. On the other hand, performing a
routine coagulation screen in patients without clinically
apparent bleeding disorders was proven unnecessary when
endobronchial biopsy was planned. Taking bronchial biopsy has
been shown to prolong flexible bronchoscopy by about 5
minutes; this might be relevant in children with impaired
ventilation.
References
1. Barbato A et al. Epithelial Damage and Angiogenesis in the
Airways of Children with Asthma. Am J
2006;
174:
Respir Crit Care Med.
975-981
2. Pohunek P. et al. Markers of eosinophilic inflammation and
tissue re-modelling in children before clinically diagnosed
bronchial asthma. Pediatr Allergy Immunology, 2005; 16 (1):
43–51
3. Barbato A et al. Airway Inflammation in Childhood Asthma.
Am J
Respir Crit Care Med. 2003; 168: 798-803
4. Gaillard et al., Airway epithelial damage and inflammation
in children with recurrent bronchitis. Am J Respir Crit Care
Med. 1994; Sep;150(3):810-7
5. Salva P et al., Safety of endobronchial biopsy in 170
children with chronic respiratory symptoms.
Thorax. 2003; 58(12): 1058–1060