Page 512 - Textbook of Pathology, 6th Edition

496 Microscopically, the features are as under:
Grossly, the lungs are firm, heavier with reduced volume.
Honeycombing (i.e. enlarged, thick-walled air spaces) i) Hallmark finding is collections of large number of
develops in parts of lung, particularly in the subpleural intraalveolar macrophages having abundant cytoplasm
region. and containing brown-black pigment and are termed as
Histologically, the changes vary according to the stage smokers’ macrophages.
of the disease. ii) The intervening septa contain a few lymphocytes,
In early stage, there is widening of the alveolar septa plasma cells and an occasional eosinophil.
by oedema and cellular infiltrate by mononuclear iii) Late cases show mild interstitial fibrosis.
inflammatory cells. The alveolar lining cells may show RESPIRATORY BRONCHIOLITIS-ASSOCIATED ILD.
hyperplasia at places and are flattened at other places. Respiratory bronchiolitis is a far more common lesion in
There is often formation of hyaline membranes. The chronic smokers than DIP and is considered a milder form
alveolar spaces contain exudate consisting of of DIP having similar clinical presentation. Respiratory
macrophages, lymphocytes and neutrophils. Many of the bronchiolitis-associated ILD is the term used for advanced
macrophages contain lamellar bodies derived from cases who develop impaired pulmonary function and
surfactant of the necrotic alveolar lining epithelial cells. radiologic features.
Based on the observation of desquamative component in The condition resolves following cessation of smoking.
the cellular exudate, some authors label the early stage of
idiopathic pulmonary fibrosis as ‘desquamative interstitial Microscopically, it is characterised by following features:
pneumonitis’. i) Patchy and bronchiolocentric location of similar
In advanced stage, there is organisation of the alveolar smokers’ macrophages as are seen in DIP.
exudate and replacement fibrosis in the alveoli as well as ii) Peribronchial infiltrate of lymphocytes and histiocytes.
in the interstitial septal wall with variable amount of iii) There may be mild peribronchial fibrosis.
inflammation. Eventually, there are small cystic areas iv) Centriacinar emphysema may coexist.
(honeycomb lung) with alternating areas of fibrosis
containing thick-walled and narrowed vessels. This stage PULMONARY LANGERHANS CELL HISTIOCYTOSIS.
is often referred to as ‘chronic interstitial pneumonitis’ or This is an uncommon smoking-related ILD occurring in
‘usual interstitial pneumonitis’. younger men (20-40 years). Clinically, the features may vary
from an asymptomatic state to a rapidly progressive course.
SECTION III
CLINICAL FEATURES. Middle-aged males are affected Symptomatic cases present with cough, dyspnoea, weight
more frequently. The usual features are of respiratory loss and fever. CT scan shows presence of ill-defined stellate
difficulty beginning with dry cough and slowly progressing nodules and thin-walled cysts.
dyspnoea. More advanced cases may develop clubbing of Discontinuation of smoking leads to reversal of the
fingers and cor pulmonale. A rapidly progressive form of condition.
the idiopathic pulmonary fibrosis with death within 6 weeks Microscopically, the features are as under:
to 6 months is termed Hamman-Rich syndrome.
i) There is presence of poorly-defined nodules distributed
in peribronchiolar location while intervening lung
ILD ASSOCIATED WITH SMOKING parenchyma is uninvolved.
ii) Characteristically, these nodules are sclerosing and
Long-term consequences of smoking is associated with contain Langerhans cells along with other inflammatory
Systemic Pathology
following non-neoplastic respiratory insufficiency:
cells.
Smoking-related COPD: due to chronic bronchitis and iii) Progressive cases have fibrosis with concomitant cystic
emphysema. change.
Smoking-related ILD: i.e. chronic restrictive pulmo-
nary disease due to desquamative interstitial pneumonia TUMOURS OF LUNGS
(DIP), respiratory bronchiolitis-associated ILD, and
pulmonary Langerhans cell histiocytosis (eosinophilic A number of benign and malignant tumours occur in the
granuloma of the lung). lungs but the primary lung cancer, commonly termed
bronchogenic carcinoma, is the most common (95% of all
DESQUAMATIVE INTERSTITIAL PNEUMONIA (DIP). primary lung tumours). The lung is also the commonest site
It is an uncommon condition occurring exclusively in for metastasis from carcinomas and sarcomas. A histologic
smokers in 4th to 5th decades of life and is more common in classification of various benign and malignant tumours of
males. Most patients present with dyspnoea and cough. lungs as recommended by the World Health Organisation is
Chest X-ray shows peculiar diffuse hazy opacities which given in Table 17.10.
characterize all ILDs. DIP was earlier thought to represent
forerunner lesion in the sequence of development of
idiopathic pulmonary fibrosis. However, DIP has minimal BRONCHOGENIC CARCINOMA
fibrosis and has a far better prognosis on cessation of smoking The term bronchogenic carcinoma is commonly used for
compared to idiopathic pulmonary fibrosis. cancer of the lungs which includes carcinomas arising from