An unusual accessory fissure of the lung.

An unusual accessory fissure of the lung found in the upper lobe of a lung on left side, during a routine dissection is reported. It cut the posterior border of the lung about 5 cm below the apex and was 1 cm deep at its commencement. It coursed forwards and downwards, across the costal surface, in a curve with its convexity directed upwards. It fell short of the anterior border by about 5 cm. It did not correspond to the usually described segmental planes of the left upper lobe.