Kundrat, speaking of the bronchopneumonia areas in influenza, says that they are characterized by the fact that in the majority of cases the exudate is comparatively rich in fibrin, as shown to the naked eye by the granularity and solidity of the exudate.
We would lay particular stress upon the fact that also Weichselbaum found this blending of purulent and fibrinous infiltrated areas in bronchopneumonia due to the influenza bacillus. The bronchopneumonic areas are "reddish brown and distinctly finely granular; other parts have rather the appearance of uniform hepatization. In the neighborhood of the purulent bronchopneumonic areas the alveoli contain, besides leukocytes, principally fibrinous exudate, whereas in other alveoli there is a serous or hemorrhagic exudate."
Below we give some statistics as to the frequency of the fibrinous and of the cellular pneumonias in influenza; the pathologic data naturally have a far greater value than the clinical data.
Birch-Hirschfeld found at the autopsies of 108 persons dying of influenza-
11 cases of croupous lobar pneumonia. 8 " " " lobular " 24 " " catarrhal
He arrives at the remarkable conclusion that "in influenza the characteristic form appears to be croupous bronchopneumonia."
We found, in the autopsies on 32 cases of influenza pneumonias, 19 croupous and 13 catarrhal, including the mixed forms.
Naunyn reports that "in Strassburg typical lobar pneumonia occurred frequently as a complication of la grippe. Three such cases ran their course with the symptoms of an asthenic pneumonia; others terminated by crisis and were typical cases of croupous pneumonia. These pneumonias developed variously, at different periods in the course of the disease-often early and very acutely, at other times insidiously, from a bronchial catarrh; nevertheless at the autopsy they were typical fibrinous infiltrations."
Eichhorst especially emphasizes, in reference to the pneumonic areas, that "only in parts was the inflammation catarrhal; elsewhere the lung showed a decided fibrinous inflammation, in spite of the lobular dissemination of the disease."
Bollinger (Munich) found, among 10 influenza pneumonias, 5 croupous lobar, 1 mixed lobar, 3 catarrhal, and 1 hypostatic pneumonia.
Marchand found, among 5 influenza pneumonias which he examined, 1 lobular pneumonia in which streptococci were found in pure culture; 1 multiple lobular pneumonia which consisted of firm, confluent areas of a brownish red color and of a rather smooth cut surface; further, 3 lobar pneumonias in the state of reddish gray or gray hepatization, "which were characterized by conspicuous softness, indicative of little fibrin and of many leukocytes." Marchand "cannot agree with the opinion that influenza pneumonia is of one particular variety only, and still less that it always depends upon a streptococcus infection, which is often probably accidental."
Menetrier reports that the influenza- pneumonias which terminated fatally "were nearly all croupous."
Hertz (Copenhagen) and Crookshank (England) emphasized the frequency of the croupous variety of pneumonia in influenza.
Weichselbaum found 7 croupous to 2 bronchopneumonias. He explains his finding of the pneumococcus in the sputum of influenza patients in the years 1889-1890 by the fact that the microscopic examination showed that in the majority of cases the inflammation of the lung was of a croupous character.
Biermer says: "The pneumonia is mostly of a catarrhal nature; croupous pneumonia also occurs, but is much rarer." Litten (German collective reports) quotes: "The characteristic of the present epidemic (1889-1890) was the frequent occurrence of croupous pneumonia, which occurred probably as often as the catarrhal form." H. Rieder (medical clinic in Munich) found, among 36 influenza pneumonias, 14 croupous (with 3 fatal cases) and 22 catarrhal (without a death). Krannhals (Riga) saw 53 cases of typical fibrinous pneumonias, 22 doubtful ones, and 37 of bronchopneumonia. Sokolowski (Warsaw) observed 14 croupous and 10 catarrhal cases. Hagenbach (Basel) especially notes that all influenza pneumonias observed in the Children's Hospital were of the croupous variety. Immermann says: "The great majority of the complicating pneumonias noted in the hospital was croupous. Demme (Children's Hospital in Berne) reports that the pneumonia was especially characterized as a catarrhal pneumonia. Yet 4 of 11 pneumonic cases had rusty sputum. Among the influenza pneumonias in the Strassburg epidemic of 1874-1875 R. von den Velden says that, "according to the course of the fever and the sputum, they were always recognized as belonging to the croupous form." Netter (Paris) describes the true croupous lobar pneumonia and its anatomic varieties, and, in particular, the frequent lobular fibrinous inflammatory areas. But: "Plus frequent que la pneumonie lobaire est la pneumonie lobulaire." Stintzing (Munich), on the other hand, characterizes the greater number of his cases of pneumonia as bronchopneumonia (15 :2), and Finkler found, among 45 cases of pneumonia, only 2 typically croupous. Guttmann, Merkel and Gut mann (Nuremberg), Albu, Lennmalm, and others saw only, or nearly exclusively, catarrhal pneumonia.
In addition to the voluminous literature already mentioned on this subject, the following extract may be added: At the meeting of the medical society of Leipsic (January 14, 1890) Heubner expressed himself in the following terms regarding the frequency of croupous pneumonia during the time of influenza: "Obviously this coincidental occurrence is not accidental. Influenza increases the disposition to acquire pneumonia, and makes the latter more severe. The character of the influenza pneumonia is an asthenic one. The severity of the secondary pleurisy is worthy of note." (Compare what has been said previously regarding pleurisy.)
These contradictions in the reports as to the frequency of both forms of pneumonia during the course of influenza are easily explained. To decide at the bedside whether we are dealing with a catarrhal or a croupous pneumonia is possible with certainty only in typical cases in which the croupous pneumonia begins and runs its course with its characteristic symptoms. These cases, however, form the minority; most of the croupous pneumonia of influenza is characterized by a completely atypical clinical pathologic course, so that the differentiation from bronchopneumonia is practically impossible. Nevertheless, I am in accord with the majority of observers and authors just quoted, not only from clinical knowledge, but from knowledge derived from the postmortem table, that the frequency of catarrhal bronchopneumonia during influenza has been considerably overrated. Physicians who, observing the onset of pneumonia in numerous small localized areas; the stoppage or the slow spread of the infiltration; the purulent character of the sputum; the onset of the disease without a chill; the remittent temperature curve; the absence of true crisis-concluded that these were cases of catarrhal bronchopneumonia, must certainly have arrived at this conclusion in many cases which were really croupous pneumonia. On the other hand, we readily admit that many cases of pneumonia complicating grip, especially the acute lobar form, may have been mistaken for croupous pneumonia, when in reality it belonged to the catarrhal variety. With the outbreak of influenza physicians were confronted with an entire novelty, for catarrhal bronchopneumonia, which up to that time had been known only as a secondary affection, arising in the course of measles, diphtheria, whooping cough, rickets, or in the latter stages of an attack of enteric fever, arising almost exclusively in children or aged persons with weakened constitutions, now appeared suddenly in the influenza epoch in an acute form, in many cases as a primary affection occurring in strong young persons who had up to that time been quite well, in whom any acute attack of pneumonia, even if it should run an atypical course, would be rightly termed croupous pneumonia.