17,1 Seabold: Dunham Fan in Roentgenograms 107 
adult cases the lesions are usually limited to the trunks of the 
upper lobes and more particularly the first interspace trunk. 
In studying the linear markings of a given trunk, if we find 
that they are cottony or faintly obscured as by a cloud effect, 
and if the fan appears to be wide open, active tuberculosis must 
be considered. Should the linear markings be sharply defined, 
dense, and show sharp studding beyond the trunk, with the fan 
partially closed, a healed lesion is to be suspected. 
Caseous bronchopneumonia gives us a picture showing a def- 
inite, heavy, flocculent density, usually in the more dependent 
portions of the lungs, and rarely in the apices. The fan pre- 
viously described may or may not be seen; if the lesion is small 
and near the pleura, it is usually walled off by a heavy septum 
with flocculent densities beyond the trunk. If the lesion is 
large, it is frequently impossible to make out the borders of the 
triangles. With a condition such as this there is usually an old 
lesion at the apex, and frequently a cavity is seen. 
The picture of miliary tuberculosis is very striking. The 
lung areas are spotted with fine, cottony granules of increased 
density, which may be discrete or confluent. These densities 
vary from the faintest shadow effects to brilliant discrete areas 
produced by calcification. The calcified areas are distinguished 
from those of anthracosis by the fact that the latter are usually 
more stellate, sharper, and thicker in character. / 
From what has been said you will readily appreciat// that the 
Dunham fan, as it is called, plays a very important rile in the 
roentgenological diagnosis of pulmonary tuberculosis, more par- 
ticularly by the stereoscopic method. Before this was used, 
Many early cases were overlooked. 
