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Infrapulmonary Effusion Masquerading as an Elevated Diaphragm

1948; Radiological Society of North America; Volume: 50; Issue: 2 Linguagem: Inglês

10.1148/50.2.223

1527-1315

James T. Taguchi, S Dressler,

Pneumothorax, Barotrauma, Emphysema

The occurrence of a pleural exudate between the inferior surface of the lung and the diaphragm is but rarely seen and rarely recognized as such when present. Roentgenologically the infrapulmonary effusion may give the appearance of an elevated, well arched diaphragm with a clear, sharp costophrenic angle and a well defined pseudo-diaphragmatic shadow. Fluoroscopically an infrapulmonary effusion may be seen to move as a unit much as does the diaphragm itself. Physical signs may be suggestive in some cases—dullness to flatness in the lower half of the chest on percussion and diminution or absence of breath sounds on auscultation. These signs, however, occur with an elevated splinted diaphragm, whatever the cause, as well as with an effusion. Fluid shift can sometimes be demonstrated fluoroscopically. The differential diagnosis from such conditions as subdiaphragmatic abscess, enlarged liver, paralysis of the diaphragm, and eventration of the diaphragm, can be safely and quickly made with the use of two procedures: (1) examination in the lateral decubitus or supine position to demonstrate shift of fluid or fluid level in the anteroposterior chest film; (2) diagnostic pneumoperitoneum. The first of these procedures is supposedly the simpler but, should the infrapulmonary effusion be completely encapsulated, a shift of the fluid cannot be expected. Diagnostic pneumoperitoneum can be done with little or no danger; it always clearly identifies the position of the diaphragm and may even demonstrate effusions too small to be detected by the positioning technic. Few cases of infrapulmonary effusions simulating an elevated diaphragm have been reported. Rigler (1) was the first to mention such cases in 1931. In two of the cases reported by him, the roentgenograms showed an elevated, arched, pseudo-diaphragmatic shadow with a clear costophrenic angle. One of his patients was a child with nephrosis; the other had a metastatic carcinoma with pleural effusion. The diagnosis in the latter case had been an elevated diaphragm due to an enlarged carcinomatous liver. Yater and Rodis (2) reported a case of tuberculous serositis in which the diaphragm was apparently elevated, but fluoroscopy demonstrated a fluid wave as well as a mediastinal shift. Postmortem examination failed to furnish any explanation for the atypical roentgen appearance of the fluid. Recently Parsonnet, Kiosk, and Bernstein (3) reported three cases of infrapulmonary transudates which occurred in congestive heart failure, and which could not be distinguished on the roentgenogram from a raised diaphragm. They demonstrated the value of pneumoperitoneum and re-emphasized the importance of the Rigler (4) positioning technic. Their third case was diagnosed only postmortem, but no explanation was offered for the atypical roentgen appearance of the pleural transudate.