Primary Atypical Pneumonia: Roentgenographic Course, Complications, Recovery Rate, and End Results

This study is a statistical analysis of 855 cases of primary atypical pneumonia of unknown etiology. It was undertaken to determine whether, from a roentgenographic point of view, reasonably accurate predictions can be made concerning the course of the disease, the recovery rate and the end result, from the original location of the pneumonia. The location of the pneumonia by lobe involvement was correlated with complications, such as pleurisy or effusion, reinfection, recurrence, clearing time, and condition of the lungs at the conclusion of the disease. Seventy-five and two tenths per cent of the cases involved one or both lower lobes, with almost equal incidence in the other 3 lobes, including multilobar involvements. The overall roentgenographic clearing time was 15.2 days with no correlation between lobe involved and recovery rate in uncomplicated cases. An average of 4 days more was required for clearing if pleurisy or effusion were complications. The presence of pleurisy or effusion bore no relation to the location of the pneumonia. Atelectasis, interlobar effusion, loculated effusion, spontaneous pneumothorax, pericardial effusion, and subcutaneous emphysema were rare complications. Ninety and nine tenths per cent recovered with completely normal lung fields. Minor permanent or semi-permanent fibrotic changes such as parietal or interlobar pleural thickening and localized parenchymal fibrosis occurred in 7 per cent, due mainly to lower lobe pneumonias. Bronchiectasis was suspected in 13 cases because of prolongation of the clearing time, but bronchography did not confirm this impression. Four cases of lower lobe pneumonia developed true bronchiectasis. Care was exercised to postpone bronchography until the disease had progressed into a subacute or chronic stage, to exclude cases of “pseudobronchiectasis.” One case of primary atypical pneumonia complicated by the development of a spontaneous subcutaneous emphysema and saccular bronchiectasis is reported in detail. Department of Radiology, Alexandria Hospital, Alexandria, Va.