|Year : 2021 | Volume
| Issue : 2 | Page : 303-307
Morphological variations of the liver and its applied significance: A cadaveric study
A Sangeetha, S Nandha Kumar
Department of Anatomy, Katuri Medical College and Hospital, Guntur, Andhra Pradesh, India
|Date of Submission||30-Jun-2019|
|Date of Acceptance||27-Jan-2020|
|Date of Web Publication||18-Oct-2021|
Dr. S Nandha Kumar
Department of Anatomy, All India Institute of Medical Sciences, Mangalagiri, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Background: Morphological features of the liver serve as important landmarks for radiologists and surgeons in the diagnosis and interpretations of liver diseases. Accessory fissures and accessory lobes often mislead the clinicians in the diagnosis of liver pathologies. Aim: This study is aimed to determine the morphological variations of the liver and implicate its clinical significance. Materials and Methods: The present study was conducted in the department of anatomy, with 50 formalin-fixed livers obtained from the cadavers of both sexes. Morphological surface features were observed, photographed, and studied. Results: About 22 (44%) livers showed variations such as accessory fissures (24%) present in the right, left, caudate, and quadrate lobe. Diaphragmatic fissures or grooves were seen in 10 (20%). Pons hepatis was seen in 3 (6%) livers. Riedels lobe was seen in 4 (8%), and the absence of quadrate lobe was seen in 1 (2%) specimen. Conclusion: The knowledge of abnormality in surface features of the liver is clinically significant and will help the radiologists and surgeons in the interpretation of normal and abnormal liver.
Keywords: Accessory fissures, accessory lobe, diaphragmatic grooves, pons hepatis, Riedel's lobe
|How to cite this article:|
Sangeetha A, Kumar S N. Morphological variations of the liver and its applied significance: A cadaveric study. J Datta Meghe Inst Med Sci Univ 2021;16:303-7
|How to cite this URL:|
Sangeetha A, Kumar S N. Morphological variations of the liver and its applied significance: A cadaveric study. J Datta Meghe Inst Med Sci Univ [serial online] 2021 [cited 2021 Dec 9];16:303-7. Available from: http://www.journaldmims.com/text.asp?2021/16/2/303/328440
| Introduction|| |
The liver is the largest abdominal organ located in the right hypochondrium, epigastrium, and left hypochondrium. The greater part of the liver is situated under the cover of the right costal margin, and the right hemidiaphragm separates it from the pleura, lungs, pericardium, and heart. The liver extends to the left to reach the left hemidiaphragm. The visceral surface of the liver is irregular in shape, and it is related to visceral organs. The liver is anatomically divided into right, left, caudate, and quadrate lobes by peritoneal reflections and ligamentous attachments. Anteriorly, it is divided by the attachment of falciform ligament, and the visceral surface is divided by the fissure for ligamentum venosum and inferiorly by fissure for ligamentum teres. The caudate and quadrate lobes are the parts of the right lobe of the liver. The gall bladder fossa is situated on the inferior surface of the right lobe. Further, each lobe is divided into segments by the branches of hepatic artery, portal vein, and bile duct. These segments are said to be functional segments of the liver. According to this type of division, a parasagittal plane passing through the gall bladder fossa divides the liver into functional right and left lobes. Segments I, II, III, and IV belong to left lobe, and Segments V, VI, VII, and VIII constitute the functional right lobe.
The liver plays a vital role in maintaining the homeostasis of the body. Any abnormality in its function leads to alterations in its size and shape., Due to increase in hepatic pathologies secondary to infections or tumors, hepatic imaging has emerged as a diagnostic tool in both accurate localization and assessment of the type of lesion of the diseased segment. These changes are diagnosed by ultrasound, computed tomography (CT), and other imaging techniques. In-depth knowledge of morphological features of the liver, its size, shape, presence of accessory lobes, and fissures is prerequisite for the clinicians in interpreting the liver anatomy for diagnostic and surgical cases. Although normal anatomical dimensions of the liver are well described, its interpersonal variability is seldom explored. Hence, the present cadaveric study was conducted to note the morphological variations of the liver and implicate its clinical relevance.
| Materials and Methods|| |
This study was conducted on 50 livers obtained from the cadavers used for teaching undergraduate students in the department of Anatomy. After removal from cadaver, they were fixed in 10% formalin. Morphological features of the right, left, caudate, and quadrate lobes were studied in detail for the size, shape, accessory fissures, and accessory lobes [Table 1]. Other variations on the surface of the livers were also noted and grouped based on Netter's classification [Table 2].
| Results|| |
In the present study, of the 50 liver specimens, 28 (56%) livers exhibited normal morphology. Of the remaining 22 (44%) specimens, several hepatic variations were observed, and they were categorized as accessory lobes, diaphragmatic grooves, accessory fissures, pons hepatis, and absence of caudate/quadrate lobes. In some of the livers, multiple anatomical variations were observed.
Enlarged right lobe with a small left lobe was observed in 4 (8%) specimens which were categorized as Type 1 Netter's [Figure 1]. Accessory fissures were seen on the visceral surface in 10 (20%) specimens [Figure 2]. In 2 (4%) of the specimens, the visceral surface showed deep renal impressions [Figure 3]. Tongue-like enlargement of the inferior border of the right lobe, commonly referred as Riedel's lobe was seen in 4 (8%) specimens [Figure 4]. In 12 (24%) specimens, multiple diaphragmatic grooves were observed on the right anterosuperior surface [Figure 5]a and [Figure 5]b.
|Figure 2: Liver showing accessory fissure, caudate process, and pons hepatis|
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|Figure 5: (a) Type 6 Netter's liver with diaphragmatic grooves. (b) Liver with prominent vertical grooves|
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A total of 8 (16%) specimens showed caudate lobe variations: 4 (8%) showed accessory fissure, elongated caudate process was seen in 2 (4%), and accessory lobe connecting to the papillary process was seen in 2 (4%) specimens [Figure 6].
Variation in the quadrate lobe was observed in 7 (14%) specimens. Horizontal fissure separating it into superior and inferior lobes was seen in 3 (6%) [Figure 6], pons hepatis of variable size and shape joining the left lobe with quadrate lobe was seen in 3 (6%) [Figure 2], and the absence of quadrate lobe was observed in 1 (2%) specimen [Figure 7].
The left lobe showed no surface variations on the anterior surface. However, in 4 (8%) specimens, the left lobe was enlarged than the right lobe which is Type 3 Netter's liver [Figure 8]. The visceral surface showed shallow fissures in 2 (4%) specimens.
The morphological variations observed in the present study were also categorized based on Netter's classification as follows: [Table 2].
| Discussion|| |
Morphological variations of the liver could be due to congenital or acquired causes. Congenital or developmental malformations are very rare in occurrence and are asymptomatic. Such variations are only incidentally reported while performing autopsy or during abdominal imaging for other visceral organ disorders. The common congenital anomalies of the liver include agenesis of the lobes, deformed lobes, and hypoplastic lobes.,
It is larger in size than the left lobe. Anatomically right lobe includes caudate lobe, quadrate lobe, and fossa for the gall bladder. In right lobar agenesis, there is an absence of the liver tissue to the right of main interlobar plane, absence of right hepatic vein, portal vein and its branches, and right intrahepatic ducts. Pathological conditions such as cirrhosis, atrophy secondary to biliary obstruction, hepatic surgery, and trauma can mimic agenesis and should be ruled out before concluding it as congenital lobar agenesis. Conventionally, based on the fissures, the lobes of the liver are classified into right, left, caudate, and quadrate lobe. In addition to this, portal fissure is also seen. Any fissure other than these is called as accessory fissures. Accessory hepatic fissures are the potential sources of diagnostic errors during imaging., Accessory fissures are seen as single or multiple thin lines on the surfaces of the liver which may be shallow or deep. These fissures are potential sites for the collection of fluid, and in liver images, it may be mistaken for a liver cyst, intrahepatic hematoma, or liver abscess., Implantation of tumor cells into these spaces may mimic intrahepatic focal lesions., In the present study, about 10 (20%) livers showed accessory fissure of varying length and depth on the visceral surface of the right lobe [Figure 2]. One of the fissure was seen on to the right of porta hepatis [Figure 2] similar to the findings reported by Singh and Rabi. This accessary fissure is called as “Rouviere's sulcus.” Rouviere's sulcus serves as an important landmark during laparascopic cholecystectomy.
About 20% of the liver in the present series showed multiple linear sulci/grooves, of varying length and depth, on the superior surface of the right lobe [Figure 5]a which is higher than reported by Joshi et al. and Chaudhari et al., In few specimens, prominent vertical grooves [Figure 5]b were observed similar to that reported by Singh and Rabi. These fissures appear due to the compression of the liver by the diaphragm. Hence, they are called as diaphragmatic grooves or sulci. Macchi et al. observed a higher incidence of about 40% of diaphragmatic grooves and reported that these grooves are weak zones of portal fissures with an underlying hepatic vein. These fissures are used as landmarks during surgical interventions to assess the plane of division.
Anatomically, the caudate lobe is a part of the right lobe, but functionally, it is part of the left lobe as it receives its blood supply from the left branches of the hepatic artery and portal vein and delivers the bile to the left hepatic duct. It has two processes along the inferior margin; the papillary process on the left and caudate process on the right connecting it to the right lobe. In the present study, a notch or fissure along the inferior border was seen in 4 (8%) specimens. Elongated caudate process simulating an accessory lobe in 2 (4%) specimens was observed, as shown in [Figure 2]. Sarala et al. found similar prominent caudate process in 9% of livers. We also observed accessory lobes in 2 (4%) specimens connecting to the left lobe mimicking an elongated papillary process [Figure 6]. Both caudate and accessory processes are a source of diagnostic errors while reporting liver pathologies. During ultrasonography, it could be mistaken as an enlarged pancreatic head or a portal lymph node.,
Normally quadrate lobe is situated between fossa for the gall bladder and fissure for ligamentum teres in the visceral surface. In the present study, 3 (6%) specimens showed transverse fissure on the quadrate lobe dividing it into superior and inferior lobes similar to the findings done by Joshi et al. In 1 (2%) specimen, it was observed that there was the absence of quadrate lobe and fissure for ligamentum teres [Figure 7]. The absence of a quadrate lobe has also been reported by Aktan et al., Nayak et al., and Gupta et al., The quadrate lobe is functionally and anatomically an independent lobe; the absence of lobe is associated with the absence of portal vein, hepatic artery, and bile duct of that lobe.
In the present study, 4 (8%) specimens showed Type 1 Netters type with a small left lobe. Left lobe hypotrophy could be congenital as reported by Demirci and Diren. In a study conducted by Aktan et al., there was the absence of the left liver lobe in 11 cases of 383 CT and one among the cadaver liver. However, in the present study, there is no absence of the left lobe, only hypotrophy was seen. In 4 (8%) specimens, we observed enlarged left lobe, with relatively small right lobe which belongs to Type 3 Netter's category [Figure 8]. Furthermore, we observed the presence of pons hepatis in 3 (6%) specimens bridging the fissure for ligamentum teres closer to porta hepatis [Figure 2]. The compression of structures underneath the pons hepatis leads to various functional abnormalities of the liver. The presence of pons hepatis should be taken into consideration by the radiologists before concluding any abnormalities of the porta hepatic structures.
Apart from the normal lobes, the presence of any extra lobes is called as accessory lobes. These lobes are due to overgrowth of the liver tissue. Based on the location of accessory lobes, clinical symptoms may vary. Riedel's lobe is one of the well-described accessory lobes, which is seen as a sessile projection from hepatic segments V and VI of the right lobes along the inferior margin. The etiology of Riedel's lobe could be a congenital or an acquired cause. Due to its extent into the right iliac fossa, torsion or trauma involving Riedel's lobe mimic the symptoms of right iliac fossa mass. In the present study, there were 4 (8%) [Figure 4] specimens, with Riedel's lobe which is higher than reported by Patil et al. and Saritha et al.,
| Conclusion|| |
Morphological variations of liver lobes are common and are asymptomatic unless diagnosed incidentally. Detail anatomical knowledge of these variations must be taken into the differential diagnosis by radiologists and surgeons. The present study reported a high incidence of Riedel's lobe and diaphragmatic grooves along with several other variations. These anatomical variations are significant for the clinician in understanding the liver morphology. Since the cadaveric studies on these parameters are scanty, the current study augments the understanding of morphological liver variations and thereby help the clinicians in their diagnosis and interventions.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
[Table 1], [Table 2]