Colonic Mucosal Pseudolipomatosis: Diagnosis and Etiology
Authored by Hussain Issa
Abstract
Background: Colonic
pseudolipomatosis is a rare condition and its pathogenesis is still not
well-known. Several mechanisms were proposed to explain its
pathogenesis. This report describes and discuss colonic
pseudolipomatosis incidentally found in a series of 8 patients
undergoing routine colonoscopy during a 5 days period.
Methods: During a 5-days period
(16-20 August 2014), we performed 25 colonoscopies and noticed the
sudden appearance of colonic pseudolipomatosis in eight of them.
Results: All underwent routine
colonoscopy and found to have sudden appearance of instantaneous white
blanching during colonoscopy. These lesions were either seen during
insertion or withdrawal of the colonoscope. Biopsy specimen was taken
from all and the biopsies showed colonic pseudolipomatosis. The
indications for colonoscopy and colonoscopic findings are shown in table
1. The sudden appearance of this cluster of cases stimulated us to
investigate and look for a possible etiology including the help of the
central sterile services department (CSSD). We found that the automated
endoscope disinfectant machine was not functioning during this week
period and the scopes disinfection was done manually. The disinfectant
used contained hydrogen peroxide.
Mucosal colonic pseudolipomatosis is a rare
colonoscopic finding with distinct endoscopic and histological findings.
It is a benign and self-limiting condition. The exact etiology of
colonic pseudolipomatosis is not known. We like others feel that
endoscopic chemical disinfectant with hydrogen peroxide is important in
the pathogenesis of colonic pseudolipomatosis rather than air-pressure
related mechanical injury during colonoscopy. Awareness of this is
important as colonic pseudolipomatosis may be confused with other
pathological conditions. Endoscopists unfamiliar with this condition
must keep this in mind as it is self-limiting and biopsies will confirm
the diagnosis.
Keywords: Mucosal colonic pseudolipomatosis; Colonoscopy; Etiology; Chemical disinfectantIntroduction
Colonic pseudolipomatosis is a rare condition and its
pathogenesis is still not well-known. Several mechanisms were proposed
to explain its pathogenesis. These include mechanical traumatic injury
to the colonic mucosa during colonoscopy, intramucosal air or chemical
injury by disinfectant [1-5]. This report describes and discusses
colonic pseudolipomatosis incidentally found in a series of 8 patients
undergoing routine colonoscopy during a one week period. The endoscopic
pattern and pathogenesis are discussed in this regard. Awareness of this
is important as these lesions can be confused with other pathological
conditions.
Patients methods and results
During a 5-days period (16-20 August 2014), we
performed 25 colonoscopies and noticed the sudden appearance of colonic
pseudolipomatosis in eight of our patients (Figures 1-6). All of them
underwent routine colonoscopy and were found to have a sudden appearance
of instantaneous white blanching during colonoscopy. These cases were
done by three different gastroenterologists. These lesions were either
seen during insertion or withdrawal of the colonoscope. Biopsy specimen
was taken from all these lesions. In all, the biopsy showed colonic
pseudolipomatosis. The biopsies sections showed colonic mucosa with no
significant inflammation. The lamina propria
contained numerous empty spaces which resemble adipose
tissue. These vacuoles are negative for CD34 and D2-40 (vascular
and lymphatic markers) and for S-100 protein (fat marker). The features
are consistent with colonic mucosal pseudolipomatosis.
No microorganisms or parasites are seen. The indications for
colonoscopy and colonoscopic findings are shown in Table 1.
Following colonoscopy all patients were asymptomatic,
and during follow up post endoscopy none of them reported
any symptoms or complications. The sudden appearance of
this cluster of cases stimulated us to investigate and look for a
possible etiology including the help of the central sterile services
department (CSSD). We found that the automated endoscope
disinfectant machine was not functioning during this week period and the scopes disinfection was done manually. The
disinfectant used contained hydrogen peroxide
Discussion
Mucosal colonic pseudolipomatosis is a rare
colonoscopic
finding. The term “colonic pseudolipomatosis” was proposed by
Snover et al. [1] in 1985 and was defined as being microscopically
similar to mucosal lipomatosis but not composed of adipocytes.
It is a benign condition with distinct endoscopic and histologic
findings and most likely caused by intramucosal air [2].
It is transient and self-limiting condition. The endoscopic
appearance of colonic pseudolipomatosis is very characteristic
and physicians should be aware of this as it may be confused
with other pathological conditions such as pseudomembranous
colitis, colonic lipomatosis, or malakoplakia. These lesions
appear as slightly elevated mucosal, whitish adherent plaques.
They are often multiple and sometimes confluent. They may
be small in size measuring few millimeters or extend to
measure 4-5 cm. These whitish plaques may be preceded by
the appearance of whitish foamy fluid. They can be found in
any part of the colon and the right and left colon are affected
equally [2,3]. Pathologically, these plaques are similar to fat but
are characterized by the presence of intramucosal gas trapped
empty spaces in the lamina propria. Although they resemble fat,
they however differ from lipomatosis by the absence of lipids,
which can be verified by fat-specific stains. Because of this gross
and microscopic similarity to fat, these lesions are referred to as
pseudolipomatosis [2,3,6,7].
The incidence of mucosal colonic pseudolipomatosis is
variable in different endoscopy unit ranging from 0.3-1.7%. It
was difficult to estimate the incidence in our unit as we see this
condition rarely. We were surprised by the sudden appearance of
a cluster of eight cases over a short period of one week.
The etiology and pathogenesis of this disorder are
controversial. A number of different pathogenetic mechanisms
have been hypothesized for this condition, including intramucosal
penetration of air by mechanical injury during insufflation,
biopsy, or other procedures [2,3]. Others suggested that mucosal
colonic pseudolipomatosis is secondary to chemical injury by
disinfectants, particularly hydrogen peroxide [4,5]. This was the
case in our series. Their sudden appearance stimulated us to
investigate and look for a possible etiology. We like others thinkthat the use of hydrogen as a disinfectant contributed to the
appearance of colonic pseudolipomatosis in our patients
Conclusion
Colonic pseudolipomatosis is a rare lesion with distinct
endoscopic and histological findings. It is a benign and self-limiting
condition. The exact etiology of colonic pseudolipomatosis is not
known. We like others feel that endoscopic chemical disinfectant
with hydrogen peroxide is important in the pathogenesis of
colonic pseudolipomatosis rather than air-pressure related
mechanical injury during colonoscopy. Awareness of this is
important as colonic pseudolipomatosis may be confused with
other pathological conditions such as pseudo membranous
colitis, colonic lipomatosis, or malakoplakia. Endoscopists
unfamiliar with this condition must keep this in mind as it selflimiting
and biopsies will confirm the diagnosis.
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