Abstract: presentation of abdominal pain and constipation, with

 

 

 

Abstract:

Ameboma is a mass of granulation
tissue with peripheral fibrosis and a core of inflammation related to amebic
chronic infection. The initial presentations are usually obstruction and low
gastrointestinal bleeding. It may mimic colon carcinoma or other granulomatous
inflammatory conditions of the colon in both the clinical presentation and the
endoscopic appearance. We report a case of a 45year-old male with a presentation
of abdominal pain and constipation, with clinical, radiological and endoscopic
presentation resembling colonic carcinoma.

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Introduction:

Amoeboma
is a rare complication of invasive infection with protozoal organism Entamoeba
histolytica, it is a localized granulomatous and proliferative intraluminal thickening that
may form a
segmental mass, usually affecting ascending colon, cecum and
rectum. Globally it represents about 1.5 to 8.4% of all invasive amibiasis and
usually appears in patients without treatment or with ineffective treatments
many years after a dysentery, which may result in low gastrointestinal bleeding
and bowel obstruction 1. We report a case of colonic amoebiasis, in which the
presenting symptoms and radiological findings closely resembled an obstructing
right?sided
colonic carcinoma.

 

Case
report:

A 45-year-old male, heavy smoker and drug
addict, presented to our hospital emergency department with complaints of
persistent abdominal pain and distention for 4 days prior to presentation. On
examination patient pale and cachexic. Patients’ blood pressure was 105/73 mmHg, heart rate was 89 beats/min, and body
temperature was 37.5°C. His abdomen was distended with midline
laparotomy scar and visible peristalsis, soft on palpation with mild tenderness
over the lower abdomen, tympanic on percussion and positive bowel sounds on
auscultation. Local rectal examination was unremarkable.

 

Laboratory investigations of blood chemistry analyses were within normal (10.4
mg/dl hemoglobin, 9270 white blood cells/?l) coagulant function (49.9 s
activated partial thromboplastic time), test for human immunodeficiency virus
(HIV) was negative. Further, mildly decreased albumin (3.13g/dl), and mildly
elevated lactate dehydrogenase (358 IU/l) were revealed. Abdominal X-ray
revealed distended small bowel loops with multiple air fluid levels.

 

He was admitted in our hospital 1 month before
(on 4th June 2017) in our hospital for same compline, contrast enhanced CT revealed a swollen and
edematous colon from was done in the previous admission which
showed small bowel dilatation mainly at ilial loops down to the level of the
terminal illume and cecum as there is inflammatory wall thinking and narrowing
of the lumen, with normal remaining parts of colon. Enlarged lymph nodes
adjacent to the cecum and ileocecal junction with mild free fluid. On day 5,
Upper and lower endoscopy were done as well and showed lower esophagitis,
narrow inflamed pylorus and bulb of duodenum deformed with inflamed edematous
mucosa with sessile polyp (biopsies were taken). Lower endoscopy showed
inflamed edematous mucosa obstructing the lumen of the cecum multiple biopsies
were taken from cecum as well. Histopathology showed chronic unspecific
inflammation.

 

Surgical
treatment was indicated with provisional diagnosis of an obstructing
right­sided colonic carcinoma. Laparotomy revealed a mass in cecum and dilated
terminal ileum loops, right-sided colon resection was performed and the
resected colon was sent for histopathology and microscopy (Figure 2.).

histopathology slides of right colon showed surface ulceration with chronic
inflammatory cells, infiltrated in the colon wall and ameba trophosoits are
seen in group in the submucosa, all features are consentient with ameboma.

 

Post-operative
course was uneventful, except for abdominal wound infection which was treated
conservatively with daily dressing and backing. Patient was discharged home
after full recovery.

 

Discussion:

 Ameboma is a rare complication of amebic
colitis, occurring approximately in
1.5 to 8.4% of cases 1,
patients with long- standing or partially treated infection develop tumorous,
exophytic, cicatricial and inflammatory masses known as “amebomas” or
amebic granulomas. The tissue necrosis in amebic colitis is replaced by
extensive inflammatory reaction and psuedotumor formation, possibly because of
secondary bacterial infection that mimic colon carcinoma 2,3. Amebomas
are usually solitary, variable in size and can be up to 15 cm in diameter. Men
within the second and fifth decade of life are most commonly affected 4,5.

Symptoms include diarrhea, fever, weight loss,
rectal bleeding and in some and may cause lumen narrowing leading to bowel obstructive symptoms. The major
complications of ameboma include perforation, obstruction, intussusception,
anorectal fistula and appendicitis 6. This occurs more frequently in patients
untreated or inadequately treated during the course of an amoebic colitis 1.

However,
these masses can still be visually indistinguishable from colonic carcinoma,
and a diagnosis cannot be obtained via endoscopic study in nearly one-third of
patients 4. Differential
diagnosis must be made with Crohn’s disease, appendix abscesses in younger
patients and colon cancer or diverticulitis in the elderly 5.

Ameboma
is uncommon and is often diagnosed after surgical interventions due to insidious
onset and variability of signs and symptoms. Surgery
is rarely required and is indicated only in cases of diagnostic uncertainty or
any arising complications such as toxic megacolon 6.

In our case, the findings on imaging, mentioned
earlier, were strongly suggestive of a metastatic colonic malignancy. In
addition to that the endoscopic biopsy histopathology of the mass showed
chronic unspecific inflammation, Surgical resection was performed because of
the possibility of colonic malignancy, at laparotomy an inflammatory mass
involving the right colon was confirmed, and so the patient underwent a right
hemicolectomy. Few similar case reports, where colonic
amebiasis, mimicked an obstructing right?sided
colonic carcinoma have been reported in litleture ….. In México Rodea
and cols analyzed 25,840 urgent abdominal surgeries from 1970 to 2007, with 129
cases with colonic complications secondary to amibiasis. From the previous,
only six ameboma cases were reported, all of them in right colon, presented
with acute abdomen or intestinal obstruction signs, only
diagnosed after surgery by histopathological exam 7.

 

 

This case highlights the diagnostic uncertainty
that may occur in patients with amoebic colitis due to its ability to mimic
colonic carcinoma, particularly if there is no definite recent history of
travel to an endemic area. Colonic resection is indicated when neoplasia cannot
be excluded or emergency
care of complications such as perforation, abscess, obstruction and
intussusception 8.

 

 

 

 

 

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Rodea RH, Athié GH,
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