40 - Lung Fissure Variation in a Midwestern US Cadaveric Population

Poster Board Number: 40
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Co-authors:

Logan Jurgens - Michigan State University; Rylee Lane - Michigan State University; Amber Heard-Booth, PhD - Assistant Professor, Radiology, Michigan State University

Abstract Body : INTRODUCTION

Human lungs exhibit fissural variation that is unaddressed in anatomy textbooks and teaching materials. However, fissure morphology is important to consider in different clinical scenarios, such as infectious spread, radiological imaging, surgical approach, and mortality following lobectomy. Therefore, it is important to document the natural variation in lung morphology to inform students and professionals. Cadaveric studies from outside the US report lungs with a high frequency of incomplete fissures and accessory or missing lobes, but there is little data for US populations. Here, we report variation in lung fissure morphology for a cadaveric sample from Michigan, USA.



MATERIALS & METHODS

Fifty-four lung specimens (26 right, 28 left) from human remains donated to the Michigan State University’s Willed Body Program were removed from the thoracic cavity for study. Each fissure was assigned one of four grades following criteria proposed by Craig and Walker (1997) where, I = complete fissure with separate lobes; II = complete visceral cleft but parenchymal fusion at fissure base; III = visceral cleft evident for part of fissure; and IV = complete lobe fusion with no fissural line. For Grade III fissures, we calculated a fissure completeness ratio as the length of the open fissure divided by the length of the entire fissure.



RESULTS

For right lungs, 69% of oblique fissures were Grade I (complete), 31% were Grade II or III (incomplete), and 0% were Grade IV (absent). For the right horizontal fissure, 27% were Grade I (complete), 62% were Grade II or III (incomplete), and 11% were Grade IV (absent). For the left lungs, 68% of oblique fissures were Grade I (complete), 32% were Grade II or III (incomplete), and 0% were Grade IV (absent). For Grade III fissures, the ratio of open cleft to fissure length ranged from 0.51 to 0.84, with a mean of 0.61.



CONCLUSION

Lungs in our sample exhibited all four grades of fissure morphology. Complete fissures were most common for the right and left oblique fissures, while the right horizontal fissure was incomplete or absent in more than 70% of specimens. Our findings are consistent with those of other studies that reported greater morphological variation in the right horizontal fissure compared to the oblique fissure of either lung.



SIGNIFICANCE/IMPLICATION

Human lungs commonly exhibit variation in fissure morphology that has potential implications for clinical decision making, management, and outcomes. We should continue to document fissure variation in healthy and diseased individuals, and common variants should be included in anatomy teaching materials. To better understand the impact of this variation in clinical scenarios, future work could study fissure morphology in vivo to investigate whether morphologic types relate to comorbidities.