Chapter 15:Lung:Pleura Flashcards Preview

2H Sytem Patho: LUNGS > Chapter 15:Lung:Pleura > Flashcards

Flashcards in Chapter 15:Lung:Pleura Deck (52):

Pathologic involvement of the pleura is, most often, a __________



secondary complication of some
underlying disease.



Secondary infections and pleural adhesions are particularly commonfindings at autopsy.

Important primary disorders include

 (1) primary intrapleural bacterial infections that imply seeding of this space as an isolated focus in the course of a transient bacteremia and

(2) a primary neoplasm of the pleura: mesothelioma (discussed later).


Pleural effusion is a common manifestation of both primary and secondary pleural diseases,
which may be inflammatory or noninflammatory.

What is the normal fluid for Pleural lubrication?



Normally, no more than 15 mL of serous,
relatively acellular, clear fluid lubricates the pleural surface.


Accumulation of pleural fluid occurs
in the following settings:

Increased hydrostatic pressure, as in congestive heart failure
Increased vascular permeability, as in pneumonia
Decreased osmotic pressure, as in nephrotic syndrome
Increased intrapleural negative pressure, as in atelectasis
Decreased lymphatic drainage, as in mediastinal carcinomatosis


Serous, serofibrinous, and fibrinous pleuritis all are caused by essentially the same processes.


T or F



What is Fibrinous exudations?

Fibrinous exudations generally reflect a later, more severe exudative reaction that, in an earlier
developmental phase, might have presented as a serous or serofibrinous exudate.


The common causes of pleuritis are _____________


inflammatory diseases within the lungs, such as:

  • tuberculosis,
  • pneumonia
  • lung infarcts,
  • lung abscess, and
  • bronchiectasis


What else can cause serous or serofibrinous pleuritis?



  •  Rheumatoid arthritis,
  • disseminated lupus erythematosus,
  • uremia,
  • diffuse systemic infections,
  • other systemic disorders, and
  • metastatic involvement of the pleura can also cause serous or serofibrinous



Radiation used in therapy for tumors in the lung or mediastinum often causes a



serofibrinous pleuritis.


In most instances the serofibrinous reaction is only minimal, and the fluid
exudate is resorbed with either resolution or organization of the fibrinous component.
Accumulation of large amounts of fluid can sufficiently encroach on lung space to cause
respiratory distress


A purulent pleural exudate (empyema) usually results from what?



A purulent pleural exudate (empyema) usually results from bacterial or mycotic seeding of the
pleural space


 Most commonly, this seeding occurs by contiguous spread of organisms from
intrapulmonary infection, but occasionally,
it occurs through lymphatic or hematogenous
dissemination from a more distant source


Rarely, infections below the diaphragm, such as the
subdiaphragmatic or liver abscess, may extend by continuity through the diaphragm into the
pleural spaces, more often on the right side.


What is Empyma?

A purulent pleural exudate (empyema) usually results from bacterial or mycotic seeding of the
pleural space.



What is the characteristic of Empyma?

Empyema is characterized by loculated, yellow-green, creamy pus composed of masses of
neutrophils admixed with other leukocytes.

Although empyema may accumulate in large
volumes (up to 500 to 1000 mL), usually the volume is small, and the pus becomes localized.

Empyema may resolve, but this outcome is less common than organization of the exudate, with
the formation of dense, tough fibrous adhesions that frequently obliterate the pleural space or
envelop the lungs; either can seriously restrict pulmonary expansion.


What is true hemorrhagic pleuritis ?

True hemorrhagic pleuritis manifested by sanguineous inflammatory exudates is infrequent and
is found in hemorrhagic diatheses, rickettsial diseases, and neoplastic involvement of the
pleural cavity.


The sanguineous exudate must be differentiated from hemothorax (discussed
later). When hemorrhagic pleuritis is encountered, careful search should be made for the
presence of exfoliated tumor cells.


What is a hydrothorax?

Noninflammatory collections of serous fluid within the pleural cavities are called hydrothorax.


What is the characteristic of hydrothorax?

The fluid is clear and straw colored. Hydrothorax may be unilateral or bilateral, depending on
the underlying cause.




The most common cause of hydrothorax is ___________

cardiac failure, and for this
reason it is usually accompanied by pulmonary congestion and edema.


Transudates may
collect in any other systemic disease associated with generalized edema and are therefore
found in renal failure and cirrhosis of the liver


What is hemothorax?

The escape of blood into the pleural cavity is known as hemothorax.

It is almost invariably a
fatal complication of a ruptured aortic aneurysm or vascular trauma or it may occur postoperatively.


Pure hemothorax is readily identifiable by the _________________

large clots that accompany the fluid
component of the blood.


What is a chylothorax?

Chylothorax is an accumulation of milky fluid, usually of lymphatic origin, in the pleural cavity.




Why is Chyle milky white?

Chyle is milky white because it contains finely emulsified fats. 



Chylothorax is most often caused
by :

thoracic duct trauma or obstruction that secondarily causes rupture of major lymphatic ducts.

This disorder is encountered in malignant conditions arising within the thoracic cavity that cause
obstruction of the major lymphatic ducts.

More distant cancers may metastasize via the
lymphatics and grow within the right lymphatic or thoracic duct to produce obstruction


What is Pneumothorax?

Pneumothorax refers to air or gas in the pleural cavities and may be spontaneous, traumatic, or


Spontaneous pneumothorax may complicate any form of pulmonary disease that
causes rupture of an alveolus.


An abscess cavity that communicates either directly with the pleural space or with the lung interstitial tissue may also lead to the escape of air. In the latter
circumstance the air may dissect through the lung substance or back through the mediastinum
(interstitial emphysema), eventually entering the pleural cavity.


Pneumothorax is most
commonly associated with ____________


emphysema, asthma, and tuberculosis


 Traumatic pneumothorax is
usually caused by some perforating injury to the chest wall, but sometimes the trauma pierces
the lung and thus provides two avenues for the accumulation of air within the pleural spaces.

Resorption of the pleural space air occurs slowly in spontaneous and traumatic pneumothorax,
provided that the original communication seals itself.


Of the various forms of pneumothorax, the one that attracts greatest clinical attention is socalled
spontaneous idiopathic pneumothorax

What is it?

This entity is encountered in relatively young
people, seems to be due to rupture of small, peripheral, usually apical subpleural blebs, and
usually subsides spontaneously as the air is resorbed.

Recurrent attacks are common and can
be quite disabling.


Pneumothorax may have as much clinical significance as a fluid collection in the lungs because:


it also causes compression, collapse, and atelectasis of the lung and may be responsible for
marked respiratory distress. 


Occasionally the lung collapse is marked. When the defect acts as a flap valve and permits the entrance of air during inspiration but fails to permit its escape
during expiration, it effectively acts as a pump that creates the progressively increasing
pressures of tension pneumothorax, which may be sufficient to compress the vital mediastinal
structures and the contralateral lung



What is tension pneumothorax?

 tension pneumothorax, which may be sufficient to compress the vital mediastinal
structures and the contralateral lung


The pleura may be involved by primary or secondary tumors.


Secondary metastatic involvement
is far more common than are primary tumors.


T or F



 The most frequent metastatic malignancies arise
from ___________.



primary neoplasms of the lung and breast


In addition to these cancers, malignancy from
any organ of the body may spread to the pleural spaces.

Ovarian carcinomas, for example,
tend to cause widespread implants in both the abdominal and thoracic cavities.



In most
metastatic involvements, a serous or serosanguineous effusion follows that often contains
neoplastic cells.

For this reason, careful cytologic examination of the sediment is of considerable diagnostic value.


What is benign mesothelioma” or “benign fibrous mesothelioma?

Previously called “benign mesothelioma” or “benign fibrous mesothelioma” in the pleura and
“fibroma” in the lung, solitary fibrous tumor is now recognized as a soft-tissue tumor with a
propensity to occur in the pleura and, less commonly, in the lung, as well as other sites.

tumor is often attached to the pleural surface by a pedicle It may be small (1 to 2 cm in
diameter) or may reach an enormous size, but it tends to remain confined to the surface of the
lung (


What is the appearance of “benign mesothelioma” or “benign fibrous mesothelioma grossly?



Grossly, it consists of dense fibrous tissue with occasional cysts filled with
viscid fluid


What is the appearance of “benign mesothelioma” or “benign fibrous mesothelioma microscopically?

microscopically, the tumor shows whorls of reticulin and collagen fibers among which
are interspersed spindle cells resembling fibroblasts.

Rarely, this tumor may be malignant, with
pleomorphism, mitotic activity, necrosis, and large size (>10 cm).






This feature can be diagnostically useful in
distinguishing these lesions from malignant mesotheliomas (which show the opposite
phenotype). The solitary fibrous tumor has no relationship to asbestos exposure.

The tumor cells are CD34+
and keratin-negative by immunostaining. 


FIGURE 15-49 Solitary fibrous tumor. Cut surface is solid with a whorled appearance


What is Malignant mesotheliomas?

Malignant mesotheliomas in the thorax arise from either the visceral or the parietal
pleura. [161,] [162]

Though uncommon, they have assumed great importance in the past few
years because of their increased incidence among people with heavy exposure to asbestos
(see “Pneumoconioses”).


In coastal areas with shipping industries in the United States and Great Britain, and in Canadian, Australian, and South African mining areas, as many as 90% of
reported mesotheliomas are asbestos-related. 

The lifetime risk of developing mesothelioma in
heavily exposed individuals is as high as 7% to 10%. There is a long latent period of 25 to 45
years for the development of asbestos-related mesothelioma, and there seems to be no
increased risk of mesothelioma in asbestos workers who smoke.

This is in contrast to the risk of
asbestos-related lung carcinoma, already high, which is markedly magnified by smoking . Thus,
for asbestos workers (particularly those who are also smokers) , the risk of dying of lung
carcinoma far exceeds that of developing mesothelioma.


Asbestos bodies (see Fig. 15-20 ) are found in increased numbers in the lungs of patients with
mesothelioma. Another marker of asbestos exposure, the asbestos plaque, has been previously


Cytogenetic studies have shown that approximately 60% to 80% of malignant mesotheliomas
have deletions in chromosomes :.


There is
a low frequency of p53 mutations, although p53 accumulation can be detected
immunohistochemicallyin 70% of malignant mesotheliomas.


Some but not all studies have
demonstrated the presence of SV40 (simian virus 40) viral DNA sequences in 60% to 80% of
pleural malignant mesotheliomas and in a smaller fraction of peritoneal mesotheliomas. The
SV40 T-antigen is a potent carcinogen that binds to and inactivates several critical regulators of
growth, such as p53 and RB. Whether SV40 is involved in the pathogenesis of mesothelioma
remains controversial. [

1p, 3p, 6q, 9p, or 22q, and 31% have p16 mutations


Malignant mesothelioma is a diffuse lesion that spreads widely in the pleural
space and is usually associated with extensive pleural effusion and direct invasion of thoracic

. The affected lung becomes ensheathed by a thick layer of soft, gelatinous,
grayish pink tumor tissue


Microscopically, malignant mesotheliomas may be :

  • epithelioid (60%),
  • sarcomatoid (20%), or
  • mixed (20%).

This is in keeping with the fact that mesothelial cells have the potential to develop as epithelium-like cells or mesenchymal stromal cells


Describe the epitheloid type of mesothelioma.

The epithelioid type of mesothelioma consists of cuboidal, columnar, or flattened cells
forming tubular or papillary structures resembling adenocarcinoma
( Fig. 15-51A ). 

mesothelioma may at times be difficult to differentiate grossly and histologically from
pulmonary adenocarcinoma



mesothelioma may at times be difficult to differentiate grossly and histologically from
pulmonary adenocarcinoma


Features that favor mesothelioma include:

 (1) positive staining for acid mucopolysaccharide, which is inhibited by previous digestion by hyaluronidase;

(2) lack of staining for carcinoembryonic antigen and other epithelial glycoprotein antigens,
markers that are generally expressed by adenocarcinoma;

(3) strong staining for keratin
proteins, with accentuation of perinuclear rather than peripheral staining;

(4) positive staining for calretinin ( Fig. 15-51B ), Wilms tumor 1 (WT-1), cytokeratin 5/6, and D2–40; and (5) on
electron microscopy, the presence of long microvilli and abundant tonofilaments but absent microvillous rootlets and lamellar bodies ( Fig. 15-52 ).

The panel of special stains is diagnostic in a majority of cases when interpreted in the context of morphology and clinical


What is sarcomatoid type of mesothelioma?

The mesenchymal type of mesothelioma appears as a spindle cell sarcoma,
resembling fibrosarcoma (sarcomatoid type)


Describe the mixed type of mesothelioma contains

The mixed type of mesothelioma contains
both epithelioid and sarcomatoid patterns (see Fig. 15-51B ).


FIGURE 15-50 Malignant mesothelioma. Note the thick, firm, white pleural tumor tissue
that ensheaths this bisected lung.


FIGURE 15-51 Histologic variants of malignant mesothelioma.


A, Epithelioid type 

B, Mixed
type, stained for calretinin (immunoperoxidase method). The epithelial component is
strongly positive (dark brown), while the sarcomatoid component is less so.


FIGURE 15-52 Ultrastructural features of pulmonary adenocarcinoma

(A), characterized
by short, plump microvilli, contrasted with those of mesothelioma

(B), in which microvilli are
numerous, long, and slender




What is the Clinical Course of mesothelioma?

The presenting complaints are chest pain, dyspnea, and, as noted, recurrent pleural effusions.
Concurrent pulmonary asbestosis (fibrosis) is present in only 20% of individuals with pleural

The lung is invaded directly, and there is often metastatic spread to the hilar
lymph nodes and, eventually, to the liver and other distant organs.

Fifty percent of patients die
within 12 months of diagnosis, and few survive longer than 2 years.

Aggressive therapy
(extrapleural pneumonectomy, chemotherapy, radiation therapy) seems to improve this poor
prognosis in some patients with epithelioid mesothelioma.


Mesotheliomas also arise in the :



peritoneum, pericardium, tunica vaginalis, and genital tract
(benign adenomatoid tumor; see Chapter 21 ). 


Peritoneal mesotheliomas are particularly
related to heavy asbestos exposure; 50% of such patients also have pulmonary fibrosis.
Although in about 50% of cases the disease remains confined to the abdominal cavity, intestinal
involvement frequently leads to death from intestinal obstruction or inanition.


Peritoneal mesotheliomas are particularly
related to heavy asbestos exposure; 50% of such patients also have pulmonary fibrosis.
Although in about 50% of cases the disease remains confined to the abdominal cavity, intestinal
involvement frequently leads to death from intestinal obstruction or inanition.