|Year : 2014 | Volume
| Issue : 2 | Page : 440-442
Caecal amebic colitis mimicking obstructing right sided colonic carcinoma with liver metastases: A rare case
Nikhil Moorchung1, Vikram Singh1, Vadalamannati Srinivas1, Shyam Sunder Jaiswal2, Gangandeep Singh2
1 Department of Pathology, Armed Forces Medical College, Pune, Maharashtra, India
2 Department of Surgery, Armed Forces Medical College, Pune, Maharashtra, India
|Date of Web Publication||14-Jul-2014|
Department of Pathology, Armed Forces Medical College, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
Intestinal Entamoeba Histolytica infection can lead to colitis, abscess formation, colonic perforation and rarely amoeboma. We report a case of colonic amoebiasis, in which the presenting symptoms and radiological findings closely resembled an obstructing right-sided colonic carcinoma, with liver metastases.
Keywords: Amoeboma, colonic carcinoma, Entameba histolytica
|How to cite this article:|
Moorchung N, Singh V, Srinivas V, Jaiswal SS, Singh G. Caecal amebic colitis mimicking obstructing right sided colonic carcinoma with liver metastases: A rare case. J Can Res Ther 2014;10:440-2
|How to cite this URL:|
Moorchung N, Singh V, Srinivas V, Jaiswal SS, Singh G. Caecal amebic colitis mimicking obstructing right sided colonic carcinoma with liver metastases: A rare case. J Can Res Ther [serial online] 2014 [cited 2019 Dec 12];10:440-2. Available from: http://www.cancerjournal.net/text.asp?2014/10/2/440/136684
| > Introduction|| |
Amebiasis is an infectious disease caused by Entameba histolytica, and is the second leading cause of death from parasitic diseases worldwide.  It is commonly acquired by ingestion of contaminated food or water and is therefore endemic in developing countries with poor sanitation. Ten percentage of the world's population becomes infected, 90% of which are asymptomatic. 
Presentation of the intestinal illnesses can be variable ranging from asymptomatic infection, symptomatic noninvasive infection, and acute proctocolitis to fulminant colitis with perforation. 
We report a case of colonic amebiasis in which the presenting symptoms and radiological findings closely resembled an obstructing right-sided colonic carcinoma, with liver metastases.
| > Case report|| |
A 57-year-old man presented to our hospital with history of lower rightquadrant abdominal, dull aching, nonradiating pain of 5 days duration, associated with low grade fever and hematocezia (1-2episodes/day). He was a chronic alcoholic and smoker withno history of hypertension, diabetes mellitus, or tuberculosis and his human immune virus (HIV) and HBSAg status was negative.On physical examination, patient looked toxic with pulse rate of 126/min, pallor, and bilateral pedal edema was present. Abdominal region wasmildly tender, with a palpable, vague right-sided abdominal mass, measured 10 × 10 cm in size. There was no hepatosplenomegaly. On digital rectal examination, rectum was empty and examining finger was tinged with blood and mucus. Abdominal X-ray revealed dilated small bowel loops, while blood tests showed marked neutrophilic leukocytosis (white cell count, 20,000/mm 3 ) and mildly deranged liver function tests. Ultrasonography of abdomen revealed distended large bowel loops with no fluid collection in peritoneal cavity. There was dilatation of the entire ascending colon and caecum with increased wall thickness. Liver showed a heterogeneous hypoechoic lesion with irregularmargins and hyperechoic septae in the right lobe (segment 5-8), measured 8.7 × 10.3 × 9 cm in size.
Computerized tomographic (CT) scanning of the abdomen also suggested malignant caecal and an ascending colon mass lesion with neoplastic lesions in the liver. In view of clinical picture and radio imaging findings a provisional diagnosis ofan obstructing right-sided colonic carcinoma, with liver metastases was considered. Emergency surgery was arranged. During the operation, a pericolic abscess was found on the ascending colon. This was walled-off by small bowel, mesentery, and the anterior abdominal wall. Right hemicolectomy with part of ileum was removed and ileostomy was performed. Right hemicolectomy specimen, measured 40 cm in length. Omentum was adherent to the caecum. Entire wall of the caecum and ascending colon was thickened.Cut surface showed multiple ulcers in the caecum and in the ascending colon.These ulcers are covered with slough. No growth or perforation was seen [Figure 1]a and b.
On microscopic examination, characteristic flask shaped ulcers were seen [Figure 1]c. Dense mixed inflammatory infiltrate was seen-comprised of neutrophils, lymphocytes, plasma cells, and eosinophils-at places reaching up to up to the serosa [Figure 1]d. Numerous trophozoites of E. histolytica measuring, 15-50 μ in size, round with abundant cytoplasm, central round nuclei with central karyosome were seen.Most of these trophozoites showed pathognomonic erythrophagocytosis [Figure 1]e.
|Figure 1: Gross and microscopic examination findings (a) gross image of the right hemicolectomy specimen. (b) Gross image showing thickened caecal wall and ulcerated mucosa. (c) Photomicrograph (H and E, ×40) showing characteristic flask-shaped ulcer. (d) Photomicrograph (H and E, ×100) showing ulcerated mucosa with dense mixed inflammatory infiltrate going deeper into the submucosa. (1e) Photomicrograph (H and E, ×400) showing Entameba histolytica trophozoites with pathognomonic erythrophagocytois (as shown by arrows)|
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No atypical cells or evidence of malignancy was seen. Further serological testing revealed an elevated titer of E. histolytica immunoglobulin G antibody. The patient started on intravenous metronidazole and made an uneventful recovery. The liver lesions, were found to have reduced in size on a subsequent CT scan of the abdomen 4 weeks later.
| > Discussion|| |
Annually, 40-50 million symptomatic cases are reported across the globe, with 40,000-100,000 deaths each year, making this condition the second leading parasitic cause of death in the world.  Majority of the patients (90%) remain asymptomatic and live normal life. Symptomatic patients can have simple acute proctocolitis (dysentery) to severe potentially fatal acute fulminant colitis.
Only in 6-11% of patients with symptomatic infection,  amebic infection causes fulminant reaction, that leads to necrotizing colitis and perforation, peritonitis, and death. Amebic colitis case fatality ranges from 1.9-9.1% and fulminant amebic colitis has a mortality rate of greater than 40%. 
E. histolytica is a major cause of diarrhea in developing countries. The infestation starts with ingestion of the cyst of E. histolyticafrom fecally contaminated food or water. The cysts are digested in the intestinal lumen releasing trophozoites. Amebiasis may involve any part of the bowel, but it has predilection for the caecum and ascending colon.  An amebic liver abscess resulting from hematogenous spread from the GI tract is the most common extraintestinal manifestation. On an abdominal CT scan, an amebic liver abscess usually appears as a rounded, well-defined, low-density lesion, with a homogeneous septated cavity, often containing considerable fluid.
In our case, on radio imaging the liver lesions was not typical of an amebic abscess, which created diagnostic dilemma. The main differential diagnoses considered were appendicitis, colonic Crohn's disease, and colorectal neoplasia. Due to the possibility of colonic malignancy, it was decided to proceed to surgical resection.At laparotomy, an inflammatory mass involving the right colon was confirmed, and so the patient underwent a right hemicolectomy.
The conventional method for diagnosis of intestinal amebiasis is examination of stool by microscopy. The reported sensitivity of this method in identifying amebic protozoa ranges from 25 to 60%. Moreover, false positive results can occur as E. histolytica is morphologically identical to non-pathological species, such as E. dispar and E. moshkovskii.  Recent advances have introduced more sensitive and specific methods for diagnosis, which include antigen detection both in the patient's stool and serum.  Serology aids the diagnosis of amebiasis, being positive in 95% patients with amebomabut only 60% in patients with amebic colitis. 
The principal treatment for amebic colitis is with nitroimidazole therapy; metronidazole is the most commonly available drug. Even in the case of fulminant colitis with contained perforation, most patients can be successfully managed by broadspectrum antibiotics to cover the bowel flora.Surgery is rarely required, and is indicated only in cases of diagnostic uncertainty or when toxic megacolon occurs.
In the present case, the patient could have been spared surgery, had a preoperative diagnosis of amebiasis been made.Few similar case reports, where colonic amebiasis, mimicked an obstructing right-sided colonic carcinoma, with liver metastases have been reported in the literature. , Amebiasis is not uncommon in India and it should always be included as one of the differential diagnoses of acute abdomen and colonic mass. This is especially so when the patient gives a recent history of dysentery and travel to endemic areas. A high index of suspicion is crucial for diagnosis, and is essential to avoid unnecessary surgery.
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