Learning objectives
To review the embryology,
frequency and types of accessory liver lobes (ALL);
To describe CT and MRI findings in a range of such cases,
including those simulating disease or presenting with complications;
To discuss through a brief literature review if this anatomical variation may be associated with higher risks of malignancy.
Background
Accessory liver lobes (ALL) are an uncommon condition and consist in the presence of a supernumerary lobe of normal hepatic parenchyma in continuity with the liver.
ALL results from a congenital ectopic hepatic tissue mostly due to embryonic heteroplasia,
although in rare instances an ALL may occur after trauma or surgery1,2.
Some authors believe that ALL is associated with an autosomal recessive gene with a very low frequency.
Currently,
there are two hypotheses (A and B) on the mechanism of an ALL: (A) the embryonic...
Findings and procedure details
Classification of ALL
The accessory lobes of the liver vary in size and topography,
and the liver tissue is often connected to the main organ,
although cases of ALL completely separate of the normal liver have also been reported.
Another entity to be considered is ectopic hepatic tissue,
which is situated outside the liver without any relation to it,
usually attached to the gallbladder or intra-abdominal ligaments.
These ectopic tissues can also be found anywhere in the thoracic,
abdominal,
or pelvic cavities1,7Fig. 2.
There is...
Conclusion
Radiologists should be able to recognize the hepatic anatomy and imaging of ALL in order to not misinterpret them as malignancy and to assess possible complications.
In the absence of underlying hepatic disease,
cirrhosis,
or known cancer,
the clinical impact of these morphologic anomalies is limited.
If a patient is diagnosed with a pedunculated ALL,
surgery can be performed in order to avoid unexpected complications.
Personal information
E.
M.
Araújo 1
U.
S.
Torres 2
H.
R.
F.
Dalla Pria 3
L.
R.
Torres 1,2
M.
H.
N.
I.
Pedroso 1
D.
J.
Racy 1
G.
D'Ippolito 2,3
1.
Hospital Beneficência Portuguesa,
São Paulo,
Brazil.
2.
Grupo Fleury,
São Paulo,
Brazil.
3.
Universidade Federal de São Paulo,
São Paulo,
Brazil.
References
1- Pereira RM.
et al.
Successful management of concomitant omphalocele,
accessory hepatic lobe,
and biliary atresia in a 44-day-old boy.
J Pediatr Surg.
2005; 40:21-24.
2- Garba ES,
Ameh EA.
Isolated rupture of an accessory liver from blunt abdominal trauma in childhood.
Pediatr Surg Int.
2002; 18:62-63.
3- Elmasalme F,
et al.
Torsion of an accessory lobe of the liver in an infant.
J Pediatr Surg.
1995;30:1348-50.
4- Champetier J, et al.
A general review of anomalies of hepatic morphology and their clinical implications.
Anat...