1. Introduction {#sec0005}
===============

The upper limit of the volume of a normal gallbladder in the adult is about 60 ml. Moderate enlargement of up to 200--300 ml is common in surgical practice due to various pathological conditions; in such cases the gallbladder fundus reaches the level of the anterior superior iliac spine. However, reports of a gallbladder of extreme size -- with a weight exceeding that of the liver (1.5 kg) -- are rare. In such cases, the gallbladder has lost its usual outlines and has acquired a balloon-shaped form. We could find only eight cases in the literature from the 18th century ([Table 1](#tbl0005){ref-type="table"}). The pathogenesis of the development of a giant gallbladder remains obscure; some authors believe that it may have expanded this much due to a valve-like mechanism associated with three possible conditions: a stone(s), a tumour, or a "wandering gallbladder",[@bib0035] each of which could impair drainage and lead to almost unlimited enlargement. Giant gallbladders may present with remarkable weight loss.[@bib0040]

2. Case presentation {#sec0010}
====================

A 77-year-old woman was admitted to our hospital with a six-month history of dull pain in the right half of the abdomen that had become more severe over the previous several days; a palpable mass in the same place which the patient had not noticed before; and loss of about 15 kg in body weight. Examination revealed a slight asymmetry of the abdomen due to the right side being swollen, and a large mass on the right side of the abdomen extending from the hypochondrial region to the level of the right anterior superior iliac spine. A leucocytosis was found (11 × 10^9^ ml^−1^). An abdominal computerized axial tomography scan of the stomach and intestine was performed. The gallbladder was found to be extremely enlarged, approximately 172 mm × 161 mm × 240 mm, containing a partial septum separating its lumen into two unequal chambers. The proximal chamber included two floating stones of 12 mm and 14 mm in diameter. The posterior gallbladder wall displaced the right kidney dorsally and downwards, and its anterior wall was responsible for the distention of the right half of the anterior abdominal wall. The pericholecystitic fat tissue was wiry and contained multiple enlarged lymph nodes (up to 10 mm in size) ([Fig. 1](#fig0005){ref-type="fig"}).

At laparotomy, a giant roundish mass was discovered, coming from under the right lobe of the liver. It was covered by the greater omentum and adhered tightly to adjacent organs. It was decided to puncture and empty the sac with a trocar, which released about 3.35 L of its contents. The first portion of the fluid (about 3 L) looked whitish, cloudy, and viscous; the subsequent portion (about 350 ml) was a light-golden, transparent bile. The sac was cut open to facilitate its further dissection ([Fig. 2](#fig0010){ref-type="fig"}), and a 3 mm cystic duct was discovered, emptying into the common bile duct, which had a normal outer width of 7 mm. The patient was discharged after an uneventful postoperative period of ten days.

The inner surface of the removed organ was covered in pink cellular mucosa, and the outer surface and the width of the wall both resembled those of the stomach. The gallbladder consisted of two unequal chambers divided by a high septum: the balloon-shaped larger one which contained mucus, and the proximal, smaller one in the form of a cone, which contained bile and two cholesterol 'mulberry' stones. The inner surface of the specimen was trabecular, similar to that of the urinary bladder. Microscopically, the picture was characteristic of chronic cholecystitis. The mucosal lining of the upper chamber (containing mucus) was flattened and consistent with that of gallbladder hydrops. The mucosal lining of the lower chamber (containing bile) was tall prismatic. Both muscular bundles and connective tissue were hypertrophied markedly. A relatively limited growth of *Enterococcus faecalis* (100 CFU[1](#fn0005){ref-type="fn"}/ml) was found in the mucus; it was highly sensitive to all routine antibiotics.

At 18-month follow-up, the patient was well, sometimes working in her small garden. She did not have any symptomatic complaints. Computed tomography revealed that the outer width of the common bile duct was 8 mm. The pancreatico-biliary junction was found to be Y-shaped, forming on the level of the duodenal wall ([Fig. 3](#fig0015){ref-type="fig"}). This disproved our working hypothesis that the development of a giant gallbladder may share a common mechanism with the development of congenital choledochal cysts, as suggested by Babbitt et al.[@bib0045]

3. Discussion {#sec0015}
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To the best of the authors' knowledge, no borders have ever been proposed to distinguish between simply enlarged and giant gallbladders. We define a gallbladder as 'giant' if the volume of the organ exceeds 1.5 L, so that its weight is comparable or even exceeds the mean (estimated) weight of the adult liver. The first clinical presentation of the entity will differ from any other gallbladder disease, but instead resembles a tumour or cyst of the abdominal cavity.

Alongside a valve-like mechanism making the gallbladder distend (for example, a stone), non-obstructive ways to alter the organ drainage may exist: nervous, hydraulic, or both. In younger patients, congenital anomalies may be considered, such as a local hypogangliosis in the gallbladder neck. We believe that, alongside a valve mechanism, there must be exclusively favourable conditions for a gallbladder to become extremely enlarged without either life-threatening complications, or even significant clinical manifestations: (1) low, if any, bacterial contamination of the bile in the gallbladder; (2) good vascularization; allowing (3) an appropriate regeneration of the gallbladder wall, allowing it to continue its distension at a steady rate. Perhaps, under conditions where the cystic duct is patent intermittently, an enlarged gallbladder itself might act as a kind of trap for the hepatic bile, allowing it to enter but not exit, and thereby creating a self-reinforcing expansionary process.

4. Conclusion {#sec0020}
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The giant gallbladder is a special clinical and pathological entity of unknown origin that occurs occasionally in surgical practice. It may develop patients of any age, mimicking a gross abdominal tumour or peritoneal cyst. Both the diagnostic method and surgical treatment demand non-routine approaches; early and late follow-up results seem to be favourable. Possible effects of gallbladder enlargement (with a patent cystic duct) on biliary hydrodynamics warrant further research on biliary system hydrodynamics which might shed light on this condition.

Conflicts of interest {#sec0025}
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None.

Funding {#sec0030}
=======

None.

Ethical approval {#sec0035}
================

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Author contributions {#sec0040}
====================

Dr. Kuznetsov was an operator (a surgeon) in the case reported.

Prof. Borodach was asked to take part during the operation as a surgeon in the case reported; he has made a review of literature and translation from Russian into English as well; a contacting author.

Dr. Fedin was an operator-assistant and so called 'a surgeon-curator' in the case reported.

Dr. Khromova provided the CT diagnostics before the surgical treatment and in a remote follow-up examination in 1.5-year after the operation was performed.

The authors would like to express acknowledgements to Oxford Language Editing, Oxford University Press, UK, for both editing of this text and most kind attention; and to Dr. Lars Aanning, MD, FACS, a surgeon, Yankton SD 57078, USA, for discussion of the topic.

Colony Forming Unit.

![A computerized axial tomography scan: the right parasagittal plane. A giant gallbladder displaces both the right kidney and the anterior abdominal wall.](gr1){#fig0005}

![During the operation: the gallbladder is cut open.](gr2){#fig0010}

![A computerized axial tomography scan: the right parasagittal plane. A short common channel formed at the level of the duodenal wall is visible to the right.](gr3){#fig0015}

###### 

Case reports of giant gallbladders.

  Publication                                           Sex                                          Age      Major co-morbidity                           GB[a](#tblfn0005){ref-type="table-fn"} size (cm)   GB volume                                                              Patent cystic duct
  ----------------------------------------------------- -------------------------------------------- -------- -------------------------------------------- -------------------------------------------------- ---------------------------------------------------------------------- --------------------
  Petit, before 1750[@bib0005]                          Female                                       27--28   --                                           ?                                                  '2 \[Paris\] pintes' (about 2 L)[b](#tblfn0010){ref-type="table-fn"}   Probably
  Van Swieten, 1754[@bib0010]                           Mail                                         12       Very probable                                ?                                                  '8 libras' (about 2.6 L)[c](#tblfn0015){ref-type="table-fn"}           Yes
  Collinson[d](#tblfn0020){ref-type="table-fn"}         ?                                            ?        ?                                            ?                                                  12.5 L                                                                 ?
  Neudörfer, 1911[d](#tblfn0020){ref-type="table-fn"}   Female                                       50       --                                           ?                                                  5.25 L                                                                 Yes
  Kehr, 1913[@bib0015]                                  ?                                            ?        ?                                            ?                                                  1.5 L                                                                  ?
  Borodach et al., 2005[@bib0020]                       Female                                       67       --                                           20 × 12                                            1.5 L                                                                  Yes
  Panaro et al., 2012[@bib0025]                         ?                                            17       PFIC-2[e](#tblfn0025){ref-type="table-fn"}   43 × 21                                            2.7 L                                                                  Yes
  Liang Zong et al., 2013[@bib0030]                     Female                                       55       --                                           30 × 18                                            4.0 L                                                                  Yes
  This case                                             Female                                       77       --                                           24 × 17                                            3.3 L                                                                  Yes
                                                                                                                                                                                                                                                                                     
  Total: 9 cases                                        Female/male ratio: 5:1; not mentioned -- 3   --       2                                            --                                                 --                                                                     6 -- yes
  0 -- no                                                                                                                                                                                                                                                                            
  1 -- probably                                                                                                                                                                                                                                                                      
  2 -- not mentioned                                                                                                                                                                                                                                                                 

GB -- gallbladder.

See the chapter "Tumeurs de la Vésicule de Fiel", pp. 445--9.

See the chapter "Hepatitis et Icterus Multiplex", pp. 107--43.

After Kehr, 1913, S6--7.[@bib0015]

Progressive Familiar Intrahepatic Cholestasis, type 2.
