Radiologic features of gram-negative pneumonias in the neutropenic patient.

While gram-negative pneumonia is a frequent complication in immunosuppressed patients with malignant disease, the diagnosis is difficult to establish. Clinical and radiographic study of 195 episodes of pneumonia in 175 consecutive patients was undertaken. Chest radiographs were negative in 19% of the episodes, probably due to absence of alveolar inflammatory cell infiltrate. Radiographic patterns were classified as either alveolar or mixed alveolar and interstitial; no case of interstitial pattern alone was identified. A positive correlation was found between the neutrophil count and the presence of radiographic abnormalities. The different types of organisms could not be distinguished by the radiographic appearance. The importance of early diagnosis and prompt specific treatment is stressed.