In clinical practice congenital abnormalities of the liver are very rare (1). Many kinds of congenital abnormalities of the liver have been described: agenesis or absences of its lobes or segments, lobar atrophy or hypertrophy, transposition of the gallbladder and Riedel's lobe (2). Riedel's lobe (named after the German surgeon, Bernhard Moritz Carl Ludwig Riedel) is a downward tongue-like projection of the anterior edge of the right liver lobe to the right of the gallbladder (3). Knowledge of this anomaly is important as it does not always remain clinically latent. The possible presence of abnormal liver has to be kept in mind whenever unexplained abdominal mass is encountered (1).
A seventeen year-old girl was hospitalized in our clinic, after being transferred from another institution, with the diagnosis of right abdomen tumoral mass and abdominal discomfort. The abdomen tumoral mass was discovered incidental, during a routine abdominal ultrasonography (U.S) examination. Physical examination revealed that she had an abdominal mass (25 / 10 cm. in diameters, round shape, regular outline, renitent consistency, relatively mobile versus the adjacent structures, sensitive on examination), descending below the right costal margin and costal angle, moving with respiration, with dullness to percussion in this area, corresponding with the mid-axillary line. Biohumoral characteristics: the patient presented a total bilirubin value of 1,36 mg/dl with a direct bilirubin value 0,4 mg/dl and a GGT - 166 U/L, the other constants being within the normal range. Diagnosis was established on the basis of imagistic U.S., Doppler examination, and C.T. The C.T. showed an abdominal mass of 170/ 140/120 mm., located in the right lower abdominal quadrant and pelvis which starts from the inferior hepatic outline to the urinary bladder. The structure has the same density as the liver, develops a mass-effect on bowel loops and have lacunars hypodense uniodophile images, with dimensions between 10 to 15 mm. The M.R.I.. examination, superposable with C.T examination, showed that the mass presented a slightly modified signal compared to the healthy hepatic parenchyma, venous afferents from the right portal branch and multiple cystic lesions with biliary fluid signal (the uniformity of the signal 2 hours after injection suggest the aspect of biliary cists communicant with hepatocitar biliary pole). The venous drainage is realized by a voluminous venous branch, connected to the right hepatic vein; the cholecyst has a normal aspect (fig. 1a, 1b). The selective celiac trunk arteriography with digital subtraction confirms the vascularization aspects described on M.R.I. examination, the tumoral mass having arterial supply from the right branch of the hepatic artery (fig. 2).
The scheduled surgical intervention showed a hepatic lobe anomaly on segment VI, with tumoral hypertrophy of Riedel’s lobe, and multiple billiary cysts (fig. 3a), for which an ablation of the abnormal hepatic parenchyma was performed. The resected specimen had its own vascular pedicle which included: an arterial branch from the right hepatic artery, a portal venous branch from the right portal vein and a vein tributary to right hepatic vein (fig. 3b); on section, the resected specimen presented multiple brown-colored cysts, different from the rest of the normal hepatic parenchyma (fig. 3c). Histopathologic examination revealed: diffuse collagen fibrosis delimiting parenchymal pseudonodules by biliary ducts and pseudocysts with serous content (fig. 4).
The postoperative course was uneventful, the patient being discharged six days after surgery, on a healing course.
The medical condition known in the literature as Riedel’s lobe, was described for the first time by Corbin in 1830, then by Cruvelhier in 1834. In 1888, Riedel reported on a group of 10 cases (3). Riedel himself described this rare morphologic anomaly of hepatic lobulation as a "round tumor on the anterior side of the liver, near the gallbladder, to its right" (found in the literature also as floating lobe, "tongue like" or constriction lobe, by other authors) (3). Riedel's lobe appears to be a common variant of normal anatomy, its prevalence being dependent on age-related changes in liver size and skeletal shape (3).
The morphologic anomalies of hepatic growth can be caused either by insufficient or excessive development of the liver (4). Also, these anomalies can appear together with malformation of other structures, especially the diaphragm - diaphragmatic hernia - and the hepatic sustainability system, but also with other malformations like ectopic kidney (5, 6, 7). The morphologic anomalies caused by insufficient development of the left hepatic lobe can cause gastric volvulus, but the anomalies of the right hepatic lobe can remain asymptomatic or can cause portal hypertension (8, 9). The morphologic anomalies caused by excessive development are induced by the formation of accessory lobes, in infra-hepatic positions (10). The Riedel’s lobe is the best-known example of sesile accessory lobe (3, 10). The congenital or acquired etiology of this morphologic hepatic anomaly is still controversial. Riedel explained its appearance as a consequence of the tractions exercised by the adherential syndrome, in the context of a lithiasic cholecystitis (3). Other authors prefer to explain it in the framework of hepatic modifications caused by age or by skeletal anomalies. - ciphoscoliosis with wide thorax (1, 8).
The assumption of a congenital origin of Riedel’s lobe is supported by a congenital disembrioplasic anomaly in the development of a hepatic bud, centered by a vitelo-mesenteric vascular axis or as a direct consequence of the persistence of mesodermic septum (2, 8).
Compared to the anatomic variants, the morphologic anomalies of hepatic development are much rare. In a study conducted on 2604 scanned patients, with 99mTc - colloidal sulfur, 86 (3,3%) presented Riedel lobe, ca. 30 presented hypertrophy (83% - 25 cases - women, versus 17% - 5 cases - men) (11). Because of the rarity of this pathology and the small numbers of cases described in the literature there is no therapeutic algorithmical approach to it. For this reason, we considered it important to communicate this case of tumoral hypertrophic Riedel’s lobe resolved by surgical treatment.
In accordance with all specific data, the symptomatho-logy of this case was minimal (an abdominal discomfort, probably due to the extrinsic compression or torsion episodes). Although Riedel reported that the anomaly is seen most frequently in women (as in our case), other authors did not find significant differences in the prevalence of Riedel's lobe between sexes (3, 8). The abdominal U.S. was useful in discovering the lesion, together with the Doppler examination showing the absence of the vascular signal in the cystic lesions presented in the tumour. More specific data were obtained by the C.T, M.R.I. and arteriographic examinations (12).
Hepatic scintigraphy was not considered necessary, despite being propagated by some authors for the diagnosis of Riedel’s lobe (12, 13). There was sufficient data for a positive diagnosis and for treatment, knowing the topography of the tumors vascular pedicles. In this case, differential diagnosis was not very difficult and the main candidates; renal tumor, a large omental tumor or a hepatoma (9) could all be excluded on clinical and imagistic grounds.
The slightly modified aspect of the tumour structure is a consequence of the narrow pedicle and secondary vascular disorders due to fibrosis at this level (described as part of the natural evolution of the tumoral hypertrophy of Riedel's lobe, with narrow pedicle) (14).
The structural alterations of the hypertrophic Riedel lobe could be discerned by the macroscopic aspect of the sectioned specimen. If the parenchyma of the Riedel's lobe had had a normal aspect, we would have considered, at least theoretically, its prelevation in order to realize a "living related", hepatic transplant. This would have presented the possibility of increasing the number of available organs. The presented case evolved naturally, without complications. Possible complications found in the literature are: torsion with noisy clinical presentation, emergency surgical intervention being necessary, for preventing secondary fibrinolisis due to intratumoral ischemic lesions - and others such as metastatic lesion in Riedel's lobe after a mammal neoplasm, or hepatic hydatide cysts of the Riedel's lobe (8, 10, 13, 14).
The prognosis of tumoral hypertrophy of Riedel’s lobe is a good one, considering the early stage diagnosis, the lack of complications and the proper treatment - the best of which was the resection of the hypertrophic parenchyma.
Summarising, we can state that the Riedel's lobe, despite its reduced incidence, can pose several diagnostic problems. Not the least of these arises from the fact that most patients are asymptomatic and the diagnosis is often made as an incidental finding at the time of surgery, radiographic, or endoscopic examination, or at the time of autopsy. Accessory lobes may also simulate tumors with or without clinical signs, but in most persons this anomaly is of no clinical significance although it might erroneously be diagnosed as hepatomegaly. In cases in which the accessory lobe has a pedicle, torsion is a common event leading to discovery of the abnormal mass. In these cases (presence of clinical signs or complications of Riedel's lobe) liver resection is the best treatment.
Therefore, the imagistic examinations (U.S., C.T., M.R.I., and arteriography) have proven themselves to be extremely useful for outlining this pathology, always having in mind what Riedel himself said: "Anatomy and more anatomy is the essence of surgery".
1. Actan, Z.A., Savas, R., Pinar, Y., Arslan, O. - Lobe and segment anomalies of the liver. J. Anat. Soc. India, 2001, 50:15.
2. Coinaud, C. - Evolution and Liver Anatomy in Surgical Anatomy of the liver revisted, Paris, 1989, pag. 31-35.
3. Riedel, BMKL - Ueber den zungenfrmigen Fortsatz des rechten Leberlappens und seine pathognostische Bedeutung für die Erkrankung der Gallenblase nebst Bemerkungen über Gallensteinoperationen. Berliner klinische Wochenschrift, 1888, 25:577, 602.
4. Champetier, J., Yver, R., Letoublon, C., Vigneau, B. - A general review of anomalies of hepatic morphology and their clinical implications. Anat Clin., 1985, 7:285.
5. Couinaud, C., Perez, R., Manouvrier, J. - Riedel's lobe and the diaphragmatic fissures. Source of error in the interpretation of hepatic radiography and radioisotope scanning; Presse Med., 1968 76:2143.
6. Kolte, D.T. - Riedel's lobe associated with a diaphragmatic hernia. J Indian Med Assoc., 1964, 43:133.
7. Kakitsubata, Y., Kakitsubata, S., Watanabe, K., Natsuda, Y., Miyanaga, I. - Pelvic kidney associated with other congenital anomalies: US and CT manifestations. Radiat. Med., 1993, 11:107.
8. Gillard, J.H., Patel, M.C., Abrahams, P.H., Dixon, A.K. - Riedel's lobe of the liver: fact or fiction?; Clin Anat., 1998, 11:47.
9 Yano, K., Ohtsubo, M., Mizota, T., Kato, H., Hayashida, Y., Morita, S., Furukawa, R, Hayakawa, A. - Riedel's lobe of the liver evaluated by multiple imaging modalities.; Intern Med., 2000, 39:87.
10. VOICULESCU, B., ILIESCU, C.A. - Anatomia ficatului în Chirurgia ficatului; sub redactia I. Popescu, Ed. Universitara "Carol Davila" (Bucuresti), 2004, pag. 11-39.
11. Sham, R., Sain, A., Silver, L - Hypertrophic Riedel's lobe of the liver.; Clin Nucl Med., 1978, 3:79.
12. Chaulieu, C., Claudon, M., Regent, D., Treheux, A. - Riedel's lobe. Echotomographic aspects; J Radiol., 1982, 63:637.
13. Soo, M.S., Adatepe, M.H. - Metastatic lesions arising in a Riedel's lobe. Findings from a sulfur colloid liver-spleen scan. Clin Nucl Med., 1990, 15:814.
14. Lefaucher, C., Dupuis, E., Muller, J., Laham, A. - Torsion of Riedel's lobe. Two cases (author's transl); J Chir, 1978, 115:25.