Septal structure of incomplete interlobar fissures of the lung

We describe the anatomy of incomplete interlobar fissures with and without septal structures. Twenty-eight fused areas in specimens obtained during 21 autopsies were examined histologically. In 12 of the 28 fused areas, there was a mixture of septal structures with and without defects. In the remaining 16, there were some septal structures. Septal structures consisted of inner layers from both lobes. These results suggest that linear shadows at interlobar fissures on computed tomography do not necessarily reflect complete interlobar fissures. Assessment of incomplete interlobar fissure is important with regard to collateral ventilation and pulmonary disease processes.