[Interlobar pneumothorax]

The features of interlobar (intrafissural) pneumothorax are little known. Of the 4 cases reported here, 1 was associated with spontaneous pneumomediastinum and 3 were consecutive to pleurodesis for spontaneous pneumothorax. Interlobar pneumothorax does not occur unless pleural adhesion is present. The diagnosis is confirmed by radiography of the chest which shows an oblong air-clear area prolonged by a fissural line and corresponding, on lateral projection, to the normal fissure. This image should not be confused with that of pneumatocele, which also resolves spontaneously.