The lesion which has been described is often associated with acute bronchitis and bronchiolitis, and the alveoli immediately about the respiratory bronchioles may be filled with polynuclear leucocytes. It is very common to find large bubbles of air sharply defined within the purulent contents of the bronchiole. In some lobules the alveolar ducts, infundibula and alveoli intervening between these foci of leucocytic pneumonia are almost uniformly filled with fibrin and polynuclear leucocytes, but in other places the formation of complete layers of hyaline fibrin is in process. Bubbles of air are often seen within the alveolar ducts, and about them is an irregular layer of fibrin formed by the penetration of air into a channel previously filled with a loose network of fibrin containing serum in its meshes. The fibrin compressed against the walls of alveolar duct and infundibulum remains as a compact layer separating these structures from the alveoli which project from their walls. The bubble of air is doubtless later absorbed and replaced by serum, so that many alveolar ducts are filled with serum almost wholly free from cells, whereas alveoli outside the fibrinous membrane contain a network of fibrin with leucocytes in greater or less abundance.
In association with this fibrinous pneumonia, which has been described, hyaline thrombosis of the capillaries is not uncommon. This hyalin material within the capillaries gives reactions of fibrin, and in sections stained by the Gram-Weigert method for demonstration of fibrin, these thrombosed vessels have the appearance of capillaries irregularly injected with a blue material.
The interstitial tissue surrounding consolidated lobules is often edematous; the lymphatics are distended with serum and contain a moderate number of lymphocytes and polynuclear leucocytes.
Among the lungs which have been studied histologically, pneumococcus has been almost invariably associated with the lobular lesions which have just been described, whether hemorrhagic, leucocytic or fibrinous; the histologic changes accompanying infection of the lung with streptococcus will be described later. Pneumococcus has been cultivated from the consolidated lung and is found in section of the lung. B. influenzæ is found in cultures made from the bronchi. Table XXXVIII includes those instances in which the histology of the consolidated lung accords with the description given above.
| Table XXXVIII | |||||
|---|---|---|---|---|---|
| NO. OF AUTOPSY | CHARACTER OF LOBULAR CONSOLIDATION | PREDOMINANT TYPE OF INFLAMMATORY EXUDATE | CULTURE FROM HEART’S BLOOD | CULTURE FROM LUNG | CULTURE FROM BRONCHUS |
| 242 | Red | Fibrinous | Pneum. atyp. II | ||
| 244 | Red | Leucocytic and hemorrhagic | Pneum. IV B. inf. | Pneum. IV, B. inf. | |
| 247 | Red and gray | Fibrinous | Pneum. IV | ||
| 249 | Red and gray | Fibrinous | Pneum. III | ||
| 252 | Red and gray | Fibrinous | Pneum. II B. inf. | Pneum. II, B. inf., S. vir. | |
| 257 | Red and gray | Leucocytic | Pneum. I | B. inf., staph. | |
| 303 | Red | Fibrinous | Pneum. IV B. inf. | Pneum. IV, B. inf., staph. | |
| 314 | ? | Fibrinous | Pneum. IV | Pneum. IV | Pneum. IV, B. inf., staph. |
| 336 | Red | Fibrinous | |||
| 395 | Red and gray | Leucocytic | Pneum. atyp. II | Pneum. atyp. II | |
| 464 | Red | Leucocytic and hemorrhagic | Pneum. I B. inf. | Pneum. I, B. inf., staph. | |
| 476 | Red | Leucocytic and hemorrhagic | |||
| 498 | Red and gray | Fibrinous | S. aur. | ||
| 506 | Red | Fibrinous | Pneum. IV | Pneum. IV S. aur. | Pneum. IV, B. inf., S. aur., M. catarrh |
Pneumococcus was found in all but 2 instances, and in one of these (Autopsy 336) the only culture was from the heart’s blood and in the other (Autopsy 498) cultures were unsatisfactory because proper media were not obtainable. Pneumococci of Types I, II, II atypical, III and IV are represented in the list. B. influenzæ has been found in a considerable number of instances in which cultures have been made from the lung and in every instance in which cultures have been made from the bronchi. Staphylococci are often found in the bronchi, but in most instances they do not penetrate into the lung.
Another group of cases of lobular pneumonia are important because in association with necrosis of lung tissue recognized by the microscope hemolytic streptococci have been found in the lungs. In such instances serum is abundant and polynuclear leucocytes are relatively scant though their distribution varies considerably; in some places leucocytes are fairly abundant though elsewhere almost absent, but this distribution bears no obvious relation to the bronchioles. In some instances (Autopsies 274 and 487) red blood corpuscles are numerous but in others (Autopsies 275 and 312) they are inconspicuous. The characteristic feature of the lesion is the occurrence of patches of necrosis within which the nuclei both of exudate and of alveolar walls have partially or completely disappeared. In these areas of necrosis short chains of streptococci are found in immense number whereas in living tissue they are present in moderate number. There has been a relatively inactive inflammatory reaction, great proliferation of streptococci and necrosis of invaded tissue. The bacteriology of instances of lobular pneumonia with necrosis is shown in Table XXXIX.
| Table XXXIX | |||||
|---|---|---|---|---|---|
| NO. OF AUTOPSY | CHARACTER OF LOBULAR CONSOLIDATION | PREDOMINANT TYPE OF INFLAMMATORY EXUDATE | CULTURE FROM HEART’S BLOOD | CULTURE FROM LUNG | CULTURE FROM BRONCHUS |
| 274 | Red | Leucocytic and hemorrhagic | S. hem. | S. hem. | S. hem., staph. |
| 275 | Red and gray | Leucocytic | Pneum. IV S. hem. | S. hem., B. inf., staph. | S. hem., B. inf., staph. |
| 312 | Red and gray | Leucocytic | S. hem. | S. hem., B. inf. | S. hem., B. inf., staph. |
| 478 | Red | Leucocytic and hemorrhagic | S. hem. | S. hem. | |
Lobular pneumonia, in some of these instances at least, has been caused primarily by pneumococci; necrosis has been the result of secondary invasion by streptococci. In Autopsy 275 Pneumococcus IV has been obtained from the blood, but in the presence of streptococci has presumably disappeared from the lung and bronchus. In the case represented by Autopsy 274, Pneumococcus IV has been found in the sputum five days before death at the onset of pneumonia, but at this time no hemolytic streptococci have been found. In the case represented by Autopsy 312, Pneumococcus IV, B. influenzæ and a few colonies of hemolytic streptococci have been obtained from the sputum two days after recognition of pneumonia and five days before death.
The hemorrhagic and edematous consolidation of the early pulmonary lesions of influenzal pneumonia is their most distinctive feature. Red confluent lobular pneumonia is frequently found in those who have died within the first week following the onset of influenza. The lungs are voluminous and heavy and may weigh as much as 1,500 grams; the pleura which overlies the consolidated area is blue or plum colored and usually shows scant if any evidence of pleurisy. Scattered patches of consolidation are accurately limited to lobules, but in addition there are large areas often involving the greater part of the lobes and not infrequently situated in the lowermost part of the lower lobes. This confluent consolidation may be obviously limited by lobule boundaries. The consolidated tissue is deep red and laxly consolidated; red serous fluid escapes from the cut surface. The lesion not infrequently occurs in association with hemorrhagic peribronchiolar pneumonia.