Page 521 - Textbook of Pathology, 6th Edition

3. HAEMORRHAGIC PLEURITIS. Haemorrhagic with emphysema, asthma and tuberculosis. Other causes 505
pleuritis differs from haemothorax in having inflammatory include chronic bronchitis in an old patient, bronchiectasis,
cells or exfoliated tumour cells in the exudate. The causes of pulmonary infarction and bronchial cancer. In young
haemorrhagic pleuritis are metastatic involvement of the patients, recurrent spontaneous rupture of peripheral
pleura, bleeding disorders and rickettsial diseases. subpleural blebs may occur without any cause resulting in
disabling condition termed spontaneous idiopathic
NON-INFLAMMATORY PLEURAL EFFUSIONS pneumothorax.
These include fluid collections in the pleural cavity such as ii) Traumatic pneumothorax is caused by trauma to the
hydrothorax, haemothorax and chylothorax. chest wall or lungs, ruptured oesophagus or stomach, and
surgical operations of the thorax.
1. HYDROTHORAX. Hydrothorax is non-inflammatory iii) Therapeutic (artificial) pneumothorax used to be
accumulation of serous fluid within the pleural cavities. employed formerly in the treatment of chronic pulmonary
Hydrothorax may be unilateral or bilateral depending upon tuberculosis in which air was introduced into the pleural sac
the underlying cause. Occasionally, an effusion is limited to so as to collapse the lung and limit its respiratory movements.
part of a pleural cavity by preexisting pleural adhesions. The effects of pneumothorax due to any cause depend
The most common cause of hydrothorax, often bilateral,
is congestive heart failure. Other causes are renal failure, upon the amount of air collected in the pleural cavity. If the
quantity of air in the pleura is small, it is resorbed. Larger
cirrhosis of liver, Meig’s syndrome (Chapter 24), pulmonary volume of air collection in the pleural cavity causes dyspnoea
oedema and primary and secondary tumours of the lungs. and pain in the chest. Pneumothorax causes lung collapse
The non-inflammatory serous effusion in hydrothorax is
clear and straw-coloured and has the characteristics of and pulls the mediastinum to the unaffected side.
Occasionally, the defect in the lungs is such that it acts as
transudate with a specific gravity of under 1.012, protein flap-valve and allows entry of air during inspiration but does
content below 1 gm/dl and little cellular content.
If the fluid collection in pleural cavity is less than 300 ml not permit its escape during expiration, creating tension
(normal is less than 15 ml), no signs or symptoms are pneumothorax which requires urgent relief of pressure so as
to relieve severe dyspnoea and circulatory failure.
produced and may be apparent in chest X-ray in standing CHAPTER 17
posture as obliterated costodiaphragmatic angle. If the TUMOURS OF PLEURA
pleural cavity contains abundant fluid, it imparts a
characteristic opaque radiographic appearance to the affected Pleural tumours may be primary or secondary. In line with
side with deviation of trachea to the opposite side. In such pulmonary tumours, the secondary tumours in the pleura
cases, symptoms such as respiratory embarrassment and are more common. The only important primary tumour of
dyspnoea are produced which are promptly relieved on pleura is mesothelioma.
withdrawal of fluid.
MESOTHELIOMA
2. HAEMOTHORAX. Accumulation of pure blood in the
pleural cavity is termed as haemothorax. The most common Mesothelioma is an uncommon tumour arising from
causes of haemothorax are trauma to the chest wall or to the mesothelial lining of serous cavities, most often in pleural The Respiratory System
thoracic viscera and rupture of aortic aneurysm. It is cavity, and rarely in peritoneal cavity and pericardial sac.
important to remove the blood from the pleural cavity as Mesotheliomas are of 2 types—benign (solitary) and malignant
early as possible. Otherwise the blood will clot and organise, (diffuse). The biologic behaviour of pleural mesotheliomas is
resulting in fibrous adhesions and obliteration of the pleural usually predicted by their gross appearance—those forming
cavity. solitary, discrete masses are generally benign, whereas those
which grow diffusely are usually malignant.
3. CHYLOTHORAX. Chylothorax is an uncommon
condition in which there is accumulation of milky fluid of Benign (Solitary) Mesothelioma
lymphatic origin into the pleural cavity. Chylothorax results
most commonly from rupture of the thoracic duct by trauma Benign or solitary mesothelioma is also called as pleural
or obstruction of the thoracic duct such as by malignant fibroma. Asbestos exposure plays no role in etiology of benign
tumours, most often malignant lymphomas. Chylothorax is mesothelioma.
more often confined to the left side. Chylous effusion is milky Grossly, it consists of a solitary, circumscribed, small, firm
due to high content of finely emulsified fats in the chyle. mass, generally less than 3 cm in diameter. Cut surface
shows whorls of dense fibrous tissue.
PNEUMOTHORAX Microscopically, the tumour is predominantly composed
An accumulation of air in the pleural cavity is called of whorls of collagen fibres and reticulin with interspersed
pneumothorax. It may occur in one of the three circum- fibroblasts. Rarely, mesothelial-lined clefts are seen in the
stances: spontaneous, traumatic and therapeutic. tumour.
i) Spontaneous pneumothorax occurs due to spontaneous Benign mesothelioma causes no symptoms and is
rupture of alveoli in any form of pulmonary disease. Most detected as an incidental radiologic finding. Sometimes the
commonly, spontaneous pneumothorax occurs in association tumour is associated with systemic syndrome of