Pulmonary Abscess Secondary to Bland Pulmonary Infarction

¹ Fellow in Medicine, Mayo Foundation.
² Section on Pathologic Anatomy, Mayo Clinic.
³ Division of Medicine, Mayo Clinic.

Findings in twenty-three cases of pulmonary abscess which developed after bland pulmonary infarction are presented and are analyzed.

While the diagnosis was definitely established clinically in only three cases, it is felt that abscess formation should be suspected in any case of infarction in which leukocytosis, unremitting fever and possibly a productive cough develop subsequently.

Pulmonary infarcts are especially prone to develop in cases of cardiac decompensation and in any case of cardiac disease in which illness has been prolonged and unremitting fever has been present the possibility of abscess formation should be considered.

A distinction should be made clinically between septic and aseptic embolic infarction. The term "infected infarct" should not be used unless the mode of infection is made clear.

In so far as the pathogenesis of these abscesses is concerned, it can be concluded that their development in a region of bland infarction depends upon the following factors:

1) The size of the region of infarction: the larger the region of infarction, the better the chances for abscess formation.

2) The state of blood supply to the region of infarction and the adequacy of collateral circulation.

3) The state of the surrounding pulmonary tissue, including such factors as coexistent congestion or atelectasis.

4) Bacteriologic factors, which include the presence or absence of dental, buccal and pharyngeal infections; the presence of bronchitis; the virulence of the organisms involved, and the massiveness of the infection.

5) The indeterminate, but apparently actively operating, factor of "tissue resistance" to the development of such abscesses in what, at first sight, appears to be a very fertile field for the growth of bacteria.