Dissection of the Gallbladder

Gallbladder specimens are frequently received by histopathology departments but only rarely exhibit serious pathology. Most cholecystectomy specimens are performed for gallstone-related diseases and do not have anything sinister lurking in them. However, of the few patients who have an adenocarcinoma of the gallbladder it is not unusual for the tumour to be unsuspected prior to the operation, or possibly even during the surgery. Therefore, it is prudent to approach a cholecystectomy specimen as if there could be a concealed malignancy.

Many cholecystectomies are performed laparoscopically. The gallbladder is often opened (within a bag to catch the bile) before being taken out of the patient's abdominal cavity, in order to reduce its size and therefore the size of the incision necessary to transmit the gallbladder. This can sometimes result in gallstones not reaching the histopathology department and hence it is advisable to state if the gallbladder was received opened or not.

The gallbladder is an example of a hollow organ.

The gallbladder should be measured in three dimensions (length and two diameters) and opened along its length, avoiding incising the hepatic bed (which is the roughened region). The thickness of the wall should also be noted. A comment is usually made on the appearance of the mucosa; typically employed phrases include 'green and velvety' and 'shows yellow flecks'. It is important to state that no tumours are present (if true).

The presence or absence of gallstones should be recorded. If gallstones are found they should be described briefly and their size range stated.

The standard sampling of the gallbladder is to take blocks from the neck, body and fundus. The block of the neck should be a transverse section of the resection margin with the cystic duct; if the gallbladder is found to be harbouring any nasty surprises, this block constitutes an important margin. The blocks of the body and fundus tend to be longitudinal.

The block of the neck of the gallbladder may contain the cystic duct lymph node.

Opinion is divided as to whether the samples from the neck, body and fundus should be placed in separate cassettes or should be all placed in a single cassette. Rather than becoming embroiled in dogmatic discussions in which opinion masquerades as fact it is preferable to consider what the sampling of the gallbladder is attempting to achieve and to assign the samples to cassettes based on that.

The neck of the gallbladder constitutes a margin and on rare occasions (dysplasia or a malignant tumour) the status of this margin is crucial. It is therefore vital that the margin can be identified unequivocally in the sections, rather than the pathologist mumbling to themselves 'Hmm is this the margin or the body?'

As the cystic duct margin is typically taken as a transverse, en face margin its block will essentially be a ring of tissue and this shape should distinguish it from the longitudinal sections taken from elsewhere. However, if a mass lesion is encountered it is safest to allocate the cystic duct margin to its own block and remove any doubt.

Focal abnormalities are best also assigned their own cassette or cassettes.

In general, the standard sampling of the neck, body and fundus can all go into a single cassette. Larger gallbladders may require two or more cassettes simply to do justice to the process of sampling.

Beware of inflexible assertions that cut up of a gallbladder should never generate more than one block. The one block per gallbladder principle is a guideline and is better expressed as 'one block should be enough if safe to do so', rather like a green traffic light does not mean 'floor it regardless' but instead indicates 'you may proceed if safe to do so'.

An example description is as follows.

The specimen comprises a partially opened gallbladder that measures 35x20x15mm and has a wall thickness of up to 3mm. The gallbladder contains numerous green and yellow, faceted gallstones that range in size from 1 to 10mm. The mucosa has multiple yellow flecks. No tumour is identified.

A1) Neck
A2) Body
A3) Fundus
Representative sections.

The most commonly encountered focal lesion is an adenomyoma. Adenomyomas are usually not large and their macroscopic appearance is characteristic (if it has been met before). The simplest approach is just to embed the entire lesion.

Solitary polyps, or low numbers of polyps are dealt with by embedding all of the polyps and performing standard sampling of the background mucosa (cholesterol polyps can be handled by more frugal sampling of the polyps and standard background sampling, provided that the macroscopic diagnosis is confident). If the gallbladder has multiple non-cholesterol polyps it is often safer and simpler just to embed the entire gallbladder, working sequentially from the neck to the fundus.

Other solitary tumours (which are most likely to be an adenocarcinoma) should also be embedded in their entirety. It is important that these blocks include the full thickness of the specimen and the serosal / adventitial surface. A cholecystectomy specimen normally bears a rough region on its external surface where the gallbladder was removed from its bed on the visceral surface of the liver. This region constitutes a margin and must be included in the blocks; inking of this hepatic margin is prudent.

If the initial sample blocks of a gallbladder disclose dysplasia then the usual procedure is to embed the rest of the gallbladder.