Definition
Bronchiolar carcinoma, alveolar cell carcinoma; a carcinoma, thought
to be derived from epithelium of terminal bronchioles, in which the
neoplastic tissue extends along the alveolar walls and grows in
small masses within the alveoli; involvement may be uniformly
diffuse and massive, or nodular, or lobular; microscopically, the
neoplastic cells are cuboidal or columnar and form papillary
structures; mucin may be demonstrated in some of the cells and in
the material in the alveoli, which also includes denuded cells;
metastases in regional lymph nodes, and even in more distant sites,
are known to occur, but are infrequent.
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Radiographic Appearance
Carcinoma of the bronchus is so common and has such a
variety of symptoms and signs that it should be considered in mist
heavy smokers. Diagnosis is usually straightforward and the first
important investigation is a chest X-ray. In a smoker, clubbing,
haemoptysis, persistent chest infection or weight loss demand an
immediate X-ray of the chest.
A common radiological manifestation of bronchial carcinoma at
presentation is a pleural effusion, usually of large volume, which
rapidly re-accumulates following aspiration, is commonly blood-
stained and often contains malignant cells.
CT is useful for evaluating the infiltration, and construction of
the lesion.
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Pathology
Aetiology
Atmosheric pollution and industrial exposure to dusts, particularly
asbestos, increase the incidence of lung cancer, but the dominant
causative agent is tobacco smoke, which is responsible for 90% of
cases. The disease is unusual in non- smokers and the increased
incidence in smokers is related to the number of cigarettes
consumed. Passive smoking causes lung cancer in non-smokers.
Clinical features
Symptoms of local disease
Bronchial carcinomas frequently arise in major bronchi, and
therefore common problems include cough, haemoptysis,
breathlessness, wheeze and stidor. Some patients have diffuse,
poorly localised chest pain, and many have chest infections. Of
these symptoms, haemoptysis, progressive breathlessness and
persistent respiratory infection are the most important. A normal
chest X-ray is unusual in bronchial carcinoma, but does not exclude
a tumour.
Breathlessness
This is common in smokers who have developed generalised airways
obstruction but progressiona is usually gradual and accelerated
breathlessness commonly occurs as a tumour narrows a major airway.
Such narrowing may produce a localised wheeze and occasionally
stridor if the trachea or major bronchi are affected.
Breathlessness may also be due to the accumulation of a malignant
pleural effusion.
Chest infection
These are not uncommon in chronic heavy smokers and usually resolve
quickly when treated with antibiotics. When infection occurs distal
to a tumour, however, it frequently persists or relapses. For this
reason failure of a pneumonia to resolve is a common presentation of
bronchial carcinoma.
Extrathoracic metastasis
In bronchial carcinoma general symptoms such as lethargy, anorexia
and weight loss frequently signify disseminated disease. The most
important sites of secondary spread are liver, bone and brain, but
virtually all parts of the body can be affected.
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Treatment:
Surgery
The overall results of surgery are not good, with a 5-year survival
of about 25%, but surgery represents almost the only possibility of
cure in non-small cell lung-cancer. In considering surgery,
assessment for mediastinal spread is critical. CT scanning can be
helpful. The relatively poor results of surgery in bronchial
carcinoma reflect the widespread and early metastases so common in
this disease.
Chemotherapy
The results of chemotherapy for non-small cell tumours not suitable
for surgery are very poor and chemotherapy is largely reserved for
the treatment of small cell lung cancer. Small cell tumours can
respond dramatically to multiple drug chemotherapy.
Treatment is given at 3-4 weekly intervals over a period of several
months. A complete response to therapy with a return to normal of
the chest X-ray and disappearance of tumour at bronchoscopy can be
achieved in 25-50% of patients. A few more patients may achieve
long-term survival if radiotherapy is combined with chemotherapy.
Radiotherapy
In bronchial carcinoma the principal purpose of radiotherapy is to
produce symptomatic relief. Radiotherapy is particularly good at
controlling bone pain, haemoptysis, superior vena caval obstruction
and breathlessness due to narrowing of major airways. In carefully
selected patients, radiotherapy can produce impressive results.
Advanced bronchogenic carcinoma
As with all malignant disease, patients with advanced bronchogenic
carcinoma which is no longer responding to treatment require much
medical nursing and social support during their last months of life.
Support of the patient's family is also important. Pain is a
particularly troublesome symptom and radiotherapy may be required
for its control. Pain may also require regular analgesics. For
intractable pain peripheral nerve blockade may be necessary. Poor
appetite and lethargy can temporarily be alleviated by steroids,
which may also improve the symptoms from cerebral secondaries for a
few weeks or months. Weakness, immobility, poor food intake and
analgesics all contribute to constipation. |
Images
PA Chest radiograph and corresponding CT of a bronchial carcinoma
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