Adenomyomatous hyperplasia is now
recognized as a common condition of the gallbladder wall,
occurring in up to 8.7% of cholecystectomy specimens.
This is the most confusing lesion within the
gall bladder, which may simulate malignancy.
It is known by a variety of names
including cholecystis glandularis proliferans, adenomyomatosis,
adenomyoma, diverticular disease, intramural diverticulosis and
Adenomyomatous hyperplasia is more
common in females and its incidence increases with age.
The majority of patients present with complaints of
chronic right upper quadrant pain.
It may produce symptoms even in
the absence of cholelithiasis and it usually occurs within the fundus.
Cholelithiasis is present in 50% of cases.
The diagnosis may be made
on cholecystography or ultrasound.
There are out-pouchings
of the mucosa into the muscle coat, which is thickened up to 5 times
Some of these are
dilated, the mucosa has papillary folds, smooth muscle hypertrophy may
be seen in the neck of the gall bladder.
This may occur secondary
to muscle thickening or may be congenital.
They are usually 1.5 cm
There are three variants of adenomyomatous hyperplasia:
- Localized (or fundal)
: The localized
variant is the most
common and is also known as an adenomyoma.
examination, it is characterized by a well-formed mass in the
gallbladder fundus. The mass may have a semilunar or crescent
Cut sections of the mass have a honeycombed appearance
that is created by multiple, small cystic spaces.
spaces represent prominent epithelial invaginations (Rokitansky-Aschoff
sinuses or intramural diverticula).
- Segmental :
The segmental variant is
characterized by focal circumferential thickening in the
gallbladder wall. The segmental variant is typically
located in the body of the gallbladder, giving it an
hourglass configuration at gross inspection.
- Diffuse :
Diffuse adenomyomatous hyperplasia is characterized by diffuse
gallbladder wall thickening with intramural diverticula
that appear as cystic spaces within the wall.
Adenomyomatous hyperplasia is
histologically characterized by epithelial and smooth
Normal gallbladder epithelium lines
the epithelial structures that may extend down into the
subserosa and reach the serosa.
Hyperplastic smooth muscle
cells accompany the epithelial invaginations that contain
inspissated bile, mucus, or stones.
fibrotic changes may be present as well as metaplastic changes
(intestinal metaplasia, pyloric gland metaplasia).
changes and in situ and invasive carcinomas may arise from the
epithelium of adenomyomatous hyperplasia.
The development of carcinoma is related to the
presence of stones, chronic inflammation, and metaplastic
changes rather than adenomyomatous hyperplasia.
Thus, adenomyomatous hyperplasia is not considered a premalignant
segmental adenomyomatous hyperplasia of the gallbladder with
perineural invasion have been reported.
Perineural and intraneural
invasion was noted in the subserosal layer.
by which the epithelial structures "invaded" the perineural spaces and
the nerves is unclear but it has been suggested by the authors that
the migration of the benign glandlike structures into the nerves is
related to the production of chemotactic factors or signaling
substances and the activation of cell receptors.
have suggested that perineural invasion is due to extension and growth
of epithelial ductal structures along tissue planes of least
resistance, such as the perineural space, and growth of hyperplastic
nerve trunks in close proximity to or within epithelial structures.
The pattern of
perineural invasion in cases of adenomyomatous hyperplasia should not
be confused with adenocarcinoma.
Attention to the general architecture
of the lesion and the bland cytologic features of the glands and
ductal structures should prevent this misinterpretation.
Hyperplasia of the Gallbladder