|Year : 2022 | Volume
| Issue : 3 | Page : 154-158
Morphometric variations in lobes and fissures of the lung: A cadaveric study in Pune region of Maharashtra
Amol Ashok Shinde, Dinesh K Patel
Associate Professor, Department of Anatomy, Dr. D.Y. Patil Vidyapeeth and Medical College, Pune, Maharashtra, India
|Date of Submission||05-Apr-2022|
|Date of Decision||13-May-2022|
|Date of Acceptance||14-Jun-2022|
|Date of Web Publication||12-Aug-2022|
Amol Ashok Shinde
B-1004 Westside County Society, Near Hp Gas Godown, Pimple Gurav, Pune - 411 061, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: Fissures are formed by the pleura covering the lungs. Right lung has horizontal and oblique fissures dividing the right lung into three lobes. Left lung has only oblique fissure dividing it into two lobes. Variations such as accessory, incomplete, and absence of fissure are documented in the literature. Methodology: This is a descriptive cadaveric study undertaken to determine the incidence of variation of fissures and lobes of the lung in the Pune region of Maharashtra. Results: Variations in fissures such as accessory fissure, incomplete fissure, and horizontal fissure in the left lung are seen. A rare finding of horizontal T-shaped pattern in the middle lobe was reported in two lungs. Five-, four-, three-, two-, and single-lobed lung are found. Conclusion: Variations in the number of lobes of the lung and fissures are pivotal for pulmonologists and cardiothoracic surgeons. Clinical misinterpretation in cases of air leaks and planned lobectomy can be avoided by knowledge of these variations.
Keywords: Absence of fissure, horizontal fissure, lung lobes and lobectomy, oblique fissure, visceral pleura
|How to cite this article:|
Shinde AA, Patel DK. Morphometric variations in lobes and fissures of the lung: A cadaveric study in Pune region of Maharashtra. Natl J Clin Anat 2022;11:154-8
|How to cite this URL:|
Shinde AA, Patel DK. Morphometric variations in lobes and fissures of the lung: A cadaveric study in Pune region of Maharashtra. Natl J Clin Anat [serial online] 2022 [cited 2022 Oct 6];11:154-8. Available from: http://www.njca.info/text.asp?2022/11/3/154/353721
| Introduction|| |
Lungs are the primary organs of respiration. The lungs are covered by pleura. Parietal and visceral are the types of pleura. A double fold of visceral pleura invaginates into the lung to divide it into various lobes. This fold is called the lung fissure. The fissures divide the lung into various lobes.
During the 4th week of intrauterine life, the lung bud appears. The bud divides into two primary bronchial buds. The right bud divides into three and the left bud into four secondary bronchial buds. They branch to form tertiary bronchial buds for bronchopulmonary segments. The spaces between individual segments get obliterated, except at the principal bronchus. This leads to the formation of three and two lobes in the right and the left lung, respectively. The complete and deep fissures formed are oblique and horizontal fissures. Defective obliteration of these segments gives rise to the formation of incomplete fissure, accessory fissure, and absence of fissure.
The movement of lobes in relation to one other and expansion in a uniform manner is helped by the presence of fissures. Collateral air drift, spread of disease, and incomplete fissure sign are seen due to incomplete fissures. Normally, oblique fissure is seen in both lungs, while oblique and horizontal fissures are seen in the right lung. Right lung has superior, middle, and inferior lobes, while the left lung has superior and inferior lobes. Complete or incomplete fissures divide the lungs into complete or incomplete lobes. Knowledge about accessory and incomplete fissures is important while planning lobar resection to prevent chances of air leak.
Variations are seen in the morphology of lobes and fissures of the lungs. This study is done to find and compare the incidence of variations of fissures and lobes for regional and inter-racial variations.
| Materials and Methods|| |
It is a descriptive study conducted in the Department of Anatomy, Dr. D. Y. Patil Medical College, Pimpri, Pune. The study protocol was cleared by the institution ethics committee. The formalin-embalmed cadavers used for routine 1st MBBS dissection were used for this study. During dissection, the pectoral region was dissected to separate the pectoral muscles from their attachment to ribs. The ribs were cut by a bone cutter to remove the rib cage. Lungs were removed by cutting the structures at the hilum. The parietal pleura covering the lungs were removed to visualize the lungs with fissures. 48 lungs from 24 formalin-embalmed cadavers were used in this study. Each lung was observed for the number of lobes. A fissure running obliquely and dividing the lung into two lobes is called the oblique fissure. Similarly, a fissure placed horizontally and dividing the upper lobe of the lung from the middle lobe is called the horizontal fissure. Any fissure other than the oblique and horizontal fissure is called accessory fissure. Incomplete fissure does not divide the lung into lobes completely. No fissure seen on the lung is called a case of absence of fissure or absent fissure. Lungs with no fissures were considered as lungs with single lobe. The presence of oblique fissure and horizontal fissure was noted. Variations such as incomplete, accessory, and absent fissures were looked for.
While selecting the lungs for our study, we used the following criteria.
- Adult lungs with no gross damage.
- Lungs with injury and gross damage.
| Results|| |
Normal arrangement of lobes and fissures of lungs was seen in 77.09% and 70.84%, respectively. We found variations in the number of lobes seen in the right and left lungs. 22.91% of lungs show variation. Five lobes were seen in 2 lungs (4.16%), one on the right and one on the left side. Four lobes were seen in 2 lungs (4.16%), both on the right side. Two left lungs showed three lobes and the presence of horizontal fissure (6.25%) [Figure 1]. 29.16% show variations of fissures. Incomplete fissure was seen bilaterally in one cadaver. Oblique fissure was absent in one right and left lung. One right lung showed the absence of horizontal fissure. Complete absence of any fissure was seen in one right and one left lung.
A horizontal T-shaped pattern was seen in two lungs with five lobes. One right and one left lung showed this variation. Here, the middle lobe was divided into three lobes by a horizontal T-shaped fissure forming three lobes. The horizontal T-shaped fissure was starting from the anterior border of the lung and encompassing around 30% of the middle lobe. The fissure was deep and complete. This fissure did not extend to the hilum of the lung [Figure 2]. One cadaver showed the absence of fissure in the right lung and 5 lobes in the left lung. An Extra irregular fissure was seen in three right and two left lobes. This fissure was seen starting from the anterior border of the lung. In right lungs, it was above the horizontal fissure. No relation to hilum of the lung was noted [Figure 3]. The results are compiled in [Table 1].
|Figure 2: Right lung with five lobes showing horizontal T pattern in the middle lobe|
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|Table 1: Anatomical variations of fissures and lobes in right and left lungs|
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| Discussion|| |
Variations were seen in the number of lobes and the presence of fissures. The presence of horizontal T-shaped pattern which divided the middle lobe of the right lung into three lobes was a new and rare variation we found. The movement of lobes of lung on one another during respiration is helped by the presence of fissures. Any infection or pleurisy can lead to obliteration of the fissures. During development, the fissures that separate individual bronchopulmonary segments fuse to form oblique and horizontal fissure. Incomplete fissure and absence of fissure are seen after partial or complete obliteration of fissures. Various authors have conducted study on variations of fissures and lobes of the lung. We discussed their findings and its clinical applicability stated by them. Comparison of findings of various studies with our study is compiled in [Table 2].
|Table 2: Comparative prevalence of variations of lung fissures in various studies (in percentages)|
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Aplasia, accessory lobes, and agenesis of the lungs are rare variations documented. Variations in lung fissures such as accessory fissures can cause odd patterns in X-ray causing difficulties in diagnosis. Craig and Walker did the pioneering work of finding a classification of lungs using lobes of lungs and fissures. They graded lungs from Grade I to IV. Completeness of oblique fissure and its relation to pulmonary artery was the criterion used for the classification. Postoperative air leakage can be seen on thoracoscopic pulmonary resection in a case with incomplete fissure.
In a high-resolution computed tomography (CT)-guided study, Shedlackova Z et al. reported finding incomplete oblique fissure on the left side in 24% and on the right side in 35%. We found bilateral presence of incomplete oblique fissure in 4.16% of lungs. They found 8% incidence of accessory horizontal fissure. A higher incidence of 74% for incomplete horizontal fissure on the right side was reported by them. We found this variation in only 4.16%. They concluded that accessory and incomplete fissures are a frequently seen variation.
Altered pulmonary development may lead to variations in lobes and fissures. Unusual X-ray presentation may be seen because of variant lobes. This can lead to misinterpretation of X-ray or CT scans. Knowledge about variations in lobes and fissures will guide the appropriate planning of lobectomy and other surgeries.
Quadros et al. observed incomplete oblique fissure in 5.55% of right and 2.5% of left lungs. Accessory horizontal fissure was seen in 25% of right lungs. 11.11% of right lungs showed complete absence of horizontal fissure. Medlar and Prakash et al. reported 62.3% and 50% of right lungs with incomplete horizontal fissure; these findings are very high as compared to 4.16% in our study. Prakash et al. mentioned the presence of incomplete oblique fissure in 39.5% of right and 35.7% of left lungs, while we found incomplete oblique fissure in 8.32% and 4.16%, respectively.
Devi et al. found completely absent horizontal fissure in 9% of right lungs. We found this feature in 4.16% of right lungs. They also found complete absence of oblique fissure in 9% of left lungs. We found oblique fissure in all left lungs. They found irregular oblique fissure in 18% of right and 36.3% of left lungs. We reported irregular oblique fissure in 4.16% of lungs bilaterally.
In a cadaveric study of lobes and lung fissures, Karadkhelkar et al. found variations regarding the horizontal fissure. They reported horizontal fissure to be absent in 9.52% of lungs. In our study, we find relatively less 4.16% incidence. 16.67% of lungs showed incomplete horizontal fissure, while we did not find a single case of incomplete horizontal fissure. Their study reported 0% of cases of variation in oblique fissure. We found a single case of incomplete oblique fissure on the right and left sides. Absent oblique fissure was seen only on the right side.
Ghosh et al. conducted a multicenter cadaveric study and found absent horizontal fissure in 48% and incomplete horizontal fissure in 26% of lungs. They reported incomplete oblique fissure on the right side in 19.56% and on the left side in 13.88% of lungs. Absent horizontal fissure was seen in 2.17% on the right and 5.55% on the left side. These figures are very high as compared to our findings.
An accessory vertical fissure was seen in the middle lobe of one right lung by Sudikshya et al. This finding coincides with our findings. However, we found a vertical fissure along with a horizontal fissure making a horizontal T as seen in [Figure 2] They reported more findings of incomplete and missing horizontal fissure.
Jacob et al. reported a case of transplant of three-lobed left lung. They mentioned that there was no change in plan for surgery, but the variation should be considered during postoperative management.
In a case of bilateral spontaneous pneumothorax, Mehrabi et al. found four-lobed left lung during open thoracotomy. They concluded that spontaneous development of pneumothorax and its recurrence is affected by morphological variations of the lungs.
During routine dissection, Modgil et al. found a four-lobed right lung in a male cadaver. They opined that prior knowledge of such variations will guide the radiologists during diagnostic procedures and cardiothoracic surgeons in planning the course of the surgery.
Marginated pneumonia may be created due to accessory fissures. Air leaks are reported in postoperative patients of lobectomy. Knowledge of variations such as accessory and incomplete fissure is imperative before such surgeries.
Berhe AG et al. concluded that knowledge of variations such as incomplete fissures will guide a radiologist in the interpretation of radiological appearance of interlobar fluid in cases of pleural effusion and surgeons for planning pulmonary lobectomy and segmental resections.
Limitations of the study
Our study had a few limitations. We did not trace the hilar structures for any variation in branching for the variant lobes. Possible addition of radiological imaging may add to more objective and accurate evaluation. This study was limited to the Pune region. A larger study with more sample size will help cover a larger population.
| Conclusion|| |
Very rare variation such as five-lobed right and left lungs is seen. Horizontal T-shaped presentation in the middle lobes was seen in these lungs. We found very less incidence of incomplete fissures. Complete absence of fissures with a single lobe forming the entire lung is reported. Knowledge about variations of lobes and fissures is important for radiologists and cardiothoracic surgeons.
We are grateful to the donors and their family members who donated their bodies for medical education by cadaveric dissection. The authors sincerely thank those who donated their bodies to science so that anatomical research could be performed. Results from such research can potentially increase humankind's overall knowledge that can then improve patient care. Therefore, these donors and their families deserve our highest gratitude.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]