Pulmonary
neoplasms
Carcinoma of the bronchus is the most common
malignancy in men and the second most common (after carcinoma of the breast) in
women. A number of neoplasms affects the airways and suspicion of carcinoma of
the bronchus should prompt thorough investigation to make the diagnosis at an
early and therefore treatable stage.
Benign
tumours
Benign
tumours of the lung are uncommon and account for less than 15 per cent of
solitary lesions seen on chest radiographs. They are usually an incidental
finding on a chest
Most
benign nodules are granulomas (tuberculosis or histoplasmosis), which give the
appearance of a high-density lesion on CT. Low-density appearances are
suspicious and the nodule should be removed by excision biopsy. Less than SO per
cent of solitary nodules are benign, underlining the importance of accurate
diagnosis.
The
most common benign tumour is the pulmonary hamartoma which is really a
developmental abnormality containing mesothelial and endothelial elements. They
may be lobulated and, although unlikely to undergo malignant transformation,
they may be multicentric. Diagnosis (and definitive treatment) is achieved by
excising the lesion.
Fibroma
Fibroma is the most common mesodermal tumour
and tends to occur in the bronchi rather than the trachea. Fibromas are often
pedunculated and therefore easily removed at bronchoscopy.
Hamartoma
Hamartoma is a disorganised mass of tissue
within the lung substance containing respiratory structures. It is the result of
a developmental abnormality and malignant change is rare.
Bronchial
adenomas
Bronchial
adenomas are mainly carcinoid tumours derived from the neuroendocrine cells of
bronchial glands. Most (80 per cent) are found in the major bronchi and are characteristically slow growing and highly
vascular. Occasionally these tumours secrete hormones adenocorticotrophic
hormone
(ACTH), melanocyte-stimulating hormone or insulin]. This may be the first
presentation but usually there are recurrent chest infections, persistent cough,
haemoptysis and occasionally chest pain. Carcinoid tumours belong to a class of
tumours that are benign at one end of the scale, to those that are locally
aggressive and to the highly malignant oat cell tumour at the other end of the
scale. Surgical excision is the most appropriate treatment and regular follow-up
is advised.
Malignant
tumours
Carcinoma of the bronchus, as stated earlier,
is the most common malignancy in men and the second most common in women
(following carcinoma of the breast), resulting in over 30000 deaths per year in
the UK (Fig. 47.11). There is only a 20 per cent 1-year survival for all cases
after diagnosis and surgery represents the best chance of prolonged survival.
Accurate
diagnosis and staging of the tumour are vital if surgery is to be considered.
The real incidence of carcinoma of the bronchus earlier in the twentieth century
was probably masked by the presence of tuberculosis. Once a cure for
tuberculosis became available, the importance of carcinoma of the lung became
apparent. Cigarette smoking is undoubtedly one of the major risk factors for
developing bronchial carcinoma. To a lesser extent, atmospheric pollution and
certain occupations (radioactive ore and chromium mining) also contribute to the
problem. In the UK, the mortality from lung cancer for individuals smoking more
than 40 cigarettes per day is over 210/100 000. This compares to a mortality of
less than 4/100 000 in nonsmokers. Regular smoking causes characteristic changes
in the bronchial epithelium from hyperplasia through squamous metaplasia to
preinvasive carcinoma in situ. These
changes are to some extent reversible if smoking is stopped.
Histological
types
Many bronchial and lung tumours have more than
one cell type, and the behaviour and prognosis depend largely on the dominant
cell type seen. There are several histological types which have an important
bearing on prognosis and response to treatment.
Squamous
cell carcinoma (SCC) accounts for the majority (over 60 per cent) of lung
cancers. It is uncommon in nonsmokers and tends to be centrally placed. There
is a tendency to cavitate and metastasise outside the thoracic cavity.
Adenocarcinoma
is less common than SCC (15 per cent) in the UK but the incidence can vary in
different countries. It is more common in females and nonsmokers, and tends to
be sited in the periphery of the lung. Adenocarcinoma often metastasise widely
to the liver, brain and adrenals. The typical histological appearance is that of
gland formation and the only worthwhile treatment, if feasible, is surgical
excision (Fig. 47.12). It is important to exclude secondary adenocarcinoma
from other sites such as colon, breast and ovary.
Small
cell carcinoma metastasises widely early in its course and is therefore rarely
amenable to surgical resection. If discovered early then surgical removal has
led to increased survival, but palliative chemotherapy and radiotherapy are
Alveolar
cell carcinoma arises in the distal airways. Resection of a solitary nodule is
associated with a good prognosis but the occurrence of a multicentric pneumonic
type of alveolar cell carcinoma is associated with a poor prognosis.
Clinical
features
Clinical features of lung carcinoma depend on:
•
the site of the lesion;
•
invasion of neighbouring structures;
•
the extent of metastases.
Common
symptoms include a persistent cough, weight loss, dyspnoea and nonspecific chest
pain. Haemoptysis occurs in less than SO per cent of patients presenting for the
first time. Severe localised pain suggests chest wall invasion with the
infiltration of an intercostal nerve. Invasion of the apical area may involve
the brachial plexus leading to Pancoast’s syndrome. Dyspnoea may come from
loss of functioning lung tissue, lymphatic invasion or the development of a
large pleural effusion. Clubbing and hypertrophic pulmonary osteoarthropathy
are sometimes seen, particularly with squamous cell lesions. These features may
resolve with excision of the primary lesion. The presence of blood in a pleural
effusion suggests that the pleura is invaded. Invasion of the mediastinum may
result in hoarseness (due to recurrent laryngeal nerve involvement), dysphagia
(due to involvement of, or extrinsic pressure on, the oesophagus) and superior
vena caval obstruction. Hormonal secretion by a tumour will have predictable
pathological and physiological effects depending on the nature of the hormone.
Small cell carcinoma is associated with the development of myopathies including
the Eaton—Lambert syndrome, which is similar to myaesthenia gravis although
the weakness tends to improve with repeated movement.
Diagnosis and
staging
There are three keys to diagnosis:
•
detection of the primary lesion;
•
tissue diagnosis;
• assessment of spread (Table 47.2)
Detection
of the primary lesion. Chest radiography. The
principal investigation in detecting pulmonary pathology is a good-quality
posteroanterior chest radiograph with an additional lateral view. The
radiographic appearance will vary according to the site of the lesion and its
effects (pleural effusion, lobar collapse, raised hemidiaphragm) (Fig.
47.13).
Sputum
cytology may reveal malignant cells but the false-negative rate is high,
particularly in poorly differentiated lesions.
Bronchoscopy is used to visualise the bronchial tree and is useful in a number of
ways (Table 47.3).
Flexible bronchoscopy may be performed with the patient awake and the
oropharynx anaesthetised with topical lignocaine (Fig. 47.15). The bronchoscope is passed into the nose and through the
vocal folds under direct vision. As the scope is flexible its tip can be
directed into the segmental bronchi with ease. Tissue and sputum samples may be
obtained for diagnostic purposes. There is a greater range of movement with this
instrument but the biopsies are relatively small and the suction facility may
not be adequate. Nearly 40 per cent of biopsy diagnoses require modification
following resection.
Rigid bronchoscopy. The rigid bronchoscope requires a general anaesthetic
in most cases. However, it is ideal for therapeutic manoeuvres such as removal
of foreign bodies, aspiration of blood and thick secretions, and intraluminal
surgery (laser resection or stent placement). This instrument, introduced under
general anaesthesia, allows visualisation and generous biopsy of the lesion (Fig. 47.15).
The surgeon and the
anaesthetist share control of the airway. The view is improved by using
muscarinic premedication and paralysing agents. Continuous ECG and pulse
oximetry monitoring are now mandatory. The operator stands behind the patient
and lifts the maxilla by the upper teeth with the middle and forefinger of the
left hand. The bronchoscope rests on the left thumb as it is introduced over the
tongue in the midline. As the bronchoscope is passed under direct vision into
the oropharynx, the neck is extended and the bronchoscope is lowered and
advanced to visualise the larynx. Turning the instrument through 90degree
will help to negotiate the vocal cords. Care must be taken not to trap the
lips or tongue between the teeth and the bronchoscope and the fulcrum should be
the left thumb and not the teeth. The tracheal rings and the carina should be
easily seen. Advancing the bronchoscope into the main bronchus reveals the
orifices of the more peripheral bronchi. Operability is determined by the
proximity of a lesion to the carina and whether or not the carina is widened
(indicating inoperability from subcarinal lymph node involvement). If the
bronchoscopy is for diagnosis rather than preoperative assessment, a biopsy may
be taken. This should be done when the anaesthetist is satisfied that the
anaesthetic can be quickly reversed. The biopsy is taken and a check made for
bleeding. The anaesthetic is reversed and the patient turned on the side. This
will allow drainage and easy expectoration of any blood or secretions.
Biopsy
is hazardous under the following conditions:
•
systemic anticoagulation;
•
pulmonary hypertension.
Bronchoscopy
may not visualise the lesion unless it is in the main airways, and is inadequate
for staging operable disease. More invasive techniques of biopsy of
intrathoracic lesions are often necessary to confirm diagnosis, stage disease
and plan treatment. The options range from percutaneous needle biopsy under
radiological control to open lung biopsy (see below).
Needle biopsy. A thin needle passed into a lesion through the chest wall under local
anaesthesia gives a good yield of malignant cells. It is best reserved for large
or peripheral lesions and is performed under radiological CT control.
Pneumothoraces are common (30 per cent) but rarely require intercostal tube
drainage. Seeding in the biopsy track and haemorrhage are also reported
complications. This procedure is also used in the diagnosis of
life-threatening pneumonia where other attempts to establish a
diagnosis have failed. The contraindications are similar to those of
bronchoscopy
but include those with poor respiratory reserve in whom even a small
pneumothorax would be fatal.
The
more invasive techniques of thoracoscopy, mediastinoscopy, mediastinotomy and
open lung biopsy, are aimed at establishing a tissue diagnosis and assessing the
degree of spread (staging) which determines resectability. Mediastinoscopy or
mediastinotomy is advisable on all patients who have enlarged lymph nodes (>1
cm) on CT of the mediastinum to avoid futile thoracotomy without hope of cure.
Smaller nodes are not likely to be involved and thoracotomy may be done based on
the benefit of doubt. Whatever staging procedure is used, there will inevitably
be a small rate (<S per cent) of nonresective thoracotomies.
Mediastinoscopy. This procedure is performed under general anaesthesia with the patient
supine and the neck extended (Fig. 47.16). A transverse incision is made 2 cm
above the sternal notch and deepened until the strap muscles are reached. These
are retracted laterally and the thyroid isthmus superiorly to reveal the
pretracheal fascia. Careful blunt dissection in this plane allows direct
palpation of the paratracheal and subcarinal nodes. A mediastinoscope may be
introduced for direct visualisation and biopsy. Care must be taken to avoid
damage to the brachiocephalic vessels anteriorly.
Mediastinotomy. An incision is made through the second intercostal space to gain access
to some of the mediastinal lymph nodes on the affected side (Figs 47.17 and
47.18). Damage to the internal mammary artery and great vessels must be avoided.
Biopsy of the mediastinal lymph nodes is possible and the medial extension of
tumour can be assessed, so this technique has important application in the
staging of lung cancer.
Great
caution should be used in the presence of superior vena caval obstruction and
previous exploration is a relative contraindication. Complications include
pneumothorax and haemorrhage. These techniques may also be used in the diagnosis
of other mediastinal conditions, including:
•
lymphoma;
•
anterior mediastinal tumours;
•
thymoma;
• sarcoid or any other cause of lymphadenopathy.
Open lung biopsy. This requires a thoracotomy and is rarely performed to diagnose
carcinoma. The site of the incision is dictated by the site of the lesion.
Only 10 per cent of patients have potentially
curable lesions on presentation, so careful investigation is required to
determine which patients are operable and will benefit from a major thoracic
resection. The internationally agreed staging system [tumour, node, metastasis (TNM)]
gives some prognostic information on the natural history of the disease but it
assumes that lung cancer behaves and spreads in a progressive manner by local
invasion of the lymph nodes and then into the bloodstream. Tumours graded T2,
N1, M0 or less have a better prognosis when treated
surgically. This means that the tumour must be staged as accurately as possible
before resection (Table 47.4). Unfortunately, most lung cancers are beyond
curative treatment at the time of presentation. However, palliation is a skilled
process from which patients may benefit in terms of quality of life and
disease-free survival. If preoperative investigations suggest that a lesion is
localised and resectable then surgery should be undertaken. A number of factors
including general fitness of the patient and the lung function tests determines
the nature of treatment. Many patients are smokers and elective physiotherapy
before the operation may be worthwhile.
Following
exploration of the fissure, the lobar artery is isolated and ligated. The vein
is then divided and oversewn
At
the completion of the operation, the remaining lung is reinflated. Air leak is
common and usually settles within a number of days. Intercostal drains are
inserted to lie basally and apically. The patient is extubated in the recovery
area once ventilation is deemed adequate.
Pneumonectomy
is removal of the whole lung. This is a major undertaking and has a high
mortality rate (5—10 per cent). The
surgeon must be satisfied that the patient is fit enough to tolerate this
procedure from the preoperative work-up. This procedure is reserved for either
centrally placed tumours involving the main bronchus or those that straddle the
fissure. At thoracotomy, an inspection of the lung and direct palpation of the
mass will determine resectability and lymph node spread. Fixation of the tumour
to the aorta, heart or oesophagus implies irresectability. Involvement of the
mediastinal lymph chain is associated with a poor prognosis. In all, 5—10 per cent of
thoracotomies are exploratory only with no resection. The objective is to keep
this to a minimum but extensive conservation would deny the patient a chance of
cure.
Pneumonectomy,
if performed, involves isolation of the main pulmonary artery after the initial
exploration. An occlusive clamp is placed across the artery and, if this is
tolerated, the resection proceeds. The artery is divided and oversewn. The
pulmonary veins are then isolated and clamped. They too are divided and oversewn.
This leaves the main bronchus which is divided so that no blind stump remains (Fig.
47.21). The technique of stump closure is important if a bronchopleural
fistula is to be avoided. The tissues are carefully handled and the stump is
closed with good apposition of the sides. Topical antibiotics may be used to
prevent infection. The chest cavity is irrigated with warm saline to remove any
blood clots or debris. Some saline is left in the hemithorax to cover the
bronchial stump. The anaesthetist manually ventilates after the clamp is removed
from the tube serving the affected side. The inflation pressures are gradually
increased until the surgeon is satisfied that there is no leak present (by the
absence of bubbles in the saline). Haemostasis is vital because there is a large
space left after pneumonectomy. Drainage is a matter of preference. Some prefer
to insert drains and unclamp them for 1 minute every hour until the drainage
ceases; others prefer not to drain. The critical point is that no suction should
be applied as there is now a sealed space with the mobile mediastinum on one
side of it. The air in the pneumonectomy space is gradually absorbed and the
fluid level within the space rises (Fig. 47.22).
Thoracoscopic
lung resection. Minimally invasive surgery has become fashionable in recent
years in all forms of surgery. The thoracoscope has been used for many
years but its use was limited mainly to performing biopsies. The instrument
had a limited view and was uncomfortable to use for any length of time. All this
has changed since the advent of video-assisted thoracoscopy (Fig.
47.23). The
surgeon’s hands are freed because the camera is attached to the thoracoscope
which can be operated by an assistant; and the image is displayed on a
television screen. The surgeon is able to manipulate instruments with both hands
to perform an impressive variety of procedures. Pneumonectomy, lobectomy and
empyema drainage are all possible, but thoracoscopic procedures for common,
more minor problems is the area providing clear justification for this
technique. Lung biopsy and the treatment of recurrent pneumothorax are the most
frequent indications for this technique of operation. The principal advantage is
that a large incision is not required and therefore less postoperative pain and
a more rapid recovery should result. The scope of thoracoscopic surgery is
increasing with the modern trend of less invasive surgery. Thoracoscopic
lobectomy is now a feasible and reproducible procedure although the long-term
results remain unproven. The thoracoscope is used in staging lung and
oesophageal malignancy and in sympathectomy. Port access coronary artery surgery
will be discussed in Chapter 48.
Respiratory
infection. Many of these patients are ex smokers so basal collapse and
hypoxaemia are common postoperatively.
Persistent
air leak. Chest drains placed at the time of surgery should deal with this
problem, but occasionally the air leak becomes chronic and the remaining lung
does not expand. Re thoracotomy may then be necessary to seal the leak.
Bronchopleural
fistula. Following pneumonectomy, the space left behind is initially filled with
air. This is slowly reabsorbed and the space fills with tissue fluid. The fluid
level rises until the air is finally reabsorbed. Dehiscence of the bronchial
stump leads to the development of a bronchopleural fistula and the tissue
fluid (which is almost inevitably infected) is expectorated in large
quantities. This is a catastrophic complication with high morbidity and
mortality. The patient is laid flat with the affected side down (to prevent
infected fluid from entering the remaining lung) while arrangements are made to
site a pleural drain. Bronchopleural fistulas are unlikely to resolve with
conservative treatment and therefore some operative strategy must be tried.
There is a number of ways of sealing the fistula, from tissue glue down the
rigid bronchoscope to thoracotomy and a muscle flap to cover the bronchial
stump. Bronchoscopic sealing with tissue glue may be successful but is
difficult. Resuturing the bronchial stump may lead to healing and the
thoracotomy will allow evacuation and thorough irrigation of the pneumonectomy
space. Closure is more successful if viable tissue can be brought over the
bronchial stump. This is achieved by dissecting a pedicle of intercostal muscle
off the chest wall leaving its artery and vein intact and suturing it over the
repair. Omentum is an alternative source of pedicled tissue. If closure is not
possible or the patient will not tolerate closure, then a fenestration procedure
may be performed to allow drainage of the fluid, usually including rib
resection. Suturing the skin to the pleural surface to form a Clagett window
provides chronic management in desperate circumstances.
Hypoxaemia.
Poor oxygenation, as a result of pre-existing lung damage, pulmonary oedema from
overenthusiastic crystalloid replacement, atelectasis and bronchopneumonia, may
occur. Treatment is aimed at the underlying cause but great care must be taken
in pneumonectomy patients who are very susceptible to hypoxaemia.
Survival
Important factors in determining prognosis are the histological type of
tumour, the spread