Incomplete pulmonary interlobar fissure sign.

The author describes findings of pleural fluid in the major pulmonary interlobar fissure. Clear areas of perihilar lucency are bordered laterally by a sharp concave line, peripheral to which is opacification consistent with pleural fluid rising into the major fissure. Perihilar lucency, curvilinear demarcation, and lateral opacity indicate fluid extending into the major pulmonary fissure. The fissure is incomplete medial to the line.