JGI Prabha Sawant et al 10.5005/jp-journals-10068-0007 REVIEW ARTICLE Amebic Abscess—Is it still a Common Entity? 1Alisha Chaubal, 2Nirav Pipaliya, 3Prabha Sawant ABSTRACT studies have reported amebic liver abscess to account for three-fourths of all cases of liver abscess, with a mean Amebic liver abscess is the most common extraintestinal manifestation of amebiasis. It is seen most frequently in the age of presentation of 40 years with an alcoholic male 4-6 fourth and fifth decades of life and is more common among predominance. In a recent Indian study of 200 patients adult men and alcoholics. The infection is primarily transmit- of liver abscess, amebic liver abscess accounted for 69% ted by food and water contamination. It presents commonly of the cases.4 Another study reported a high rate of com- with fever and right hypochondriac pain but can present with plications (~30% pleuropulmonary and intraperitoneal complications like rupture into the pleural and peritoneal cavity or with abdominal vein thrombosis. The infection still rupture) but this could be due to referral bias to a surgical 5 responds well to nitroimidazoles, which remain the mainstay unit. A study in the emergency unit showed a mortality of treatment. In India, the epidemiology and presentation of of 5.8% with number of pigtail catheters inserted correlat- amebic abscess have not changed over the years and it still ing with mortality.6 Data from our institution where 200 is the major cause of liver abscesses. patients with liver abscess were analyzed over a period Keywords: Amebic, Liver abscess, Metronidazole. of 3 years, amebic liver abscess accounted for 72% of the How to cite this article: Chaubal A, Pipaliya N, Sawant P. Amebic cases, with a male to female ratio of 8:1 and an average Abscess—Is it still a Common Entity? J Gastrointest Infect 2017; age of presentation of 42 years. Most of our patients were 7(1):32-35. alcoholic (62%); however, the incidence of liver cirrhosis Source of support: Nil was low among these patients (4%). A high content of iron (present in country liquor) and carbohydrate in the Conflict of interest: None diet predisposes to invasive amebiasis.7 In developed countries, amebiasis is generally seen in migrants from INTRODUCTION and travelers to endemic areas. Sexual oral–anal contact may also account for acquisition of infection.8 The mor- Amebic liver abscess is the most common extraintestinal tality rate has been estimated to be around 0.2 to 2.0% in manifestation of amebiasis. It still accounts for less than adults and up to 26% in children.9 1% of Entamoeba histolytica infections.1 Pathogenesis Epidemiology The infection is primarily transmitted by food and water Amebic liver abscess (and other extraintestinal disease) contamination. Rarely transmission via oral/anal sex is seen most frequently in the fourth and fifth decades or direct colonic inoculation during colonoscopy has 2 of life. It is 7 to 10 times more common among adult occurred. Entamoeba histolytica exists in two forms. The men though there is equal gender distribution of colonic cyst stage is the infective form, and the trophozoite stage amebic disease. Suggested mechanisms for this gender causes invasive disease. The cyst wall is broken down by difference are alcohol consumption causing Kupffer cell trypsin in the small intestine. Trophozoites are released and 3 depression and protective effect of estrogen. Areas with colonize the cecum. To initiate symptomatic infection, E. high rates of amebic liver abscess include India, Africa, histolytica trophozoites present in the lumen must adhere Mexico, and parts of Central and South America. Indian to the underlying mucosa and penetrate the mucosal layer. Liver involvement occurs following invasion by E. histolytica into mesenteric venules. Amebae then enter 1 2 Superspeciality Medical Officer, Former Superspeciality the portal circulation and travel to the liver where they Medical Officer,3 Former Professor and Head typically form one or more abscesses. The E. histolytica 1-3 Department of Gastroenterology, Lokmanya Tilak Municipal galactose/N-acetyl-D-galactosamine lectin is an adhesion General Hospital and Lokmanya Tilak Municipal Medical 10 College, Mumbai, Maharashtra, India protein complex, which sustains tissue invasion. The abscess contains acellular proteinaceous debris, which Corresponding Author: Prabha Sawant, Former Professor and Head, Department of Gastroenterology, Lokmanya Tilak is thought to be a consequence of induced apoptosis and Municipal General Hospital and Lokmanya Tilak Municipal is surrounded by a rim of amebic trophozoites invading Medical College, Mumbai, Maharashtra, India, e-mail: the tissue. The right lobe of the liver is more commonly [email protected] affected than the left lobe. This is because the right lobe 32 JGI Amebic Abscess—Is it still a Common Entity? portal blood flow is supplied predominantly by the supe- relevant epidemiology (resident in, migration from, or rior mesenteric vein, whereas the left lobe portal blood travel to an endemic area). In such circumstances, the flow is supplied by the splenic vein. diagnosis may be supported by radiographic imaging of Risk factors for amebic liver abscess are alcoholism, the liver. In the setting of suggestive findings on imaging malignancy, human immunodeficiency virus (HIV) infec- studies, confirmatory serologic or antigenic testing tion, malnutrition, corticosteroid use, disorders of cell- should be pursued, perhaps supplemented with stool mediated immunity, and homosexual activity. Alcohol microscopy or antigenic testing of stool, with or without suppresses function of Kupffer cells (specialized macro- evaluation for the parasite in liver abscess fluid. However, phage) in liver, which clear the amebae. Defects in cell- simultaneous liver abscess and amebic colitis are uncom- mediated immunity are attributed to cause unchecked mon, so stool microscopy and polymerase chain reaction invasive amebiasis.11 (PCR) are usually negative in the setting of liver abscess. Clinical Manifestations Laboratory Investigations Patients with amebic liver abscess usually present with General findings 1 to 2 weeks of right upper quadrant pain and fever Raised bilirubin, leukocytosis (75% cases), raised trans- (38.5–39.5°C). Pain may be referred to the epigastrium, aminases and alkaline phosphatase (nonspecific), and the right chest, or the right shoulder. The pain is usually raised markers of acute inflammation may be seen. dull but may be pleuritic or aching. Other symptoms may include cough, sweating, malaise, weight loss, anorexia, Imaging and hiccoughs. Concurrent diarrhea is present in less than one-third of patients, although some patients report history Radiographic imaging of the liver can be pursued with of dysentery within the previous few months. Jaundice ultrasound, computed tomography (CT), or magnetic occurs in less than 10% of patients.2 Physical examination resonance imaging (MRI). Ultrasonography (USG) reveals hepatomegaly and point tenderness over the liver usually demonstrates a cystic intrahepatic cavity. Amebic in approximately 50% of cases. Localized tenderness in the liver abscesses are most commonly found in the right region of the abscess, most commonly at the lower right lobe; 70 to 80% are solitary subcapsular lesions, although intercostal spaces, is frequently seen. Hepatomegaly may multiple lesions can be present.15 Localization in the not be detected in patients with abscess at subdiaphrag- left lobe predisposes to extension into the pericardial matic location. Movement of the right side of the chest and sac. On ultrasound, the abscess appears as a round, diaphragm may be restricted with dullness on percussion. well-defined hypoechoic mass without significant wall Rupture of liver abscess can occur into any adjoining echoes. On CT scan, it appears as a low-density mass space or organ; extension into the chest occurs almost with a peripheral enhancing rim. On MRI, the abscess four times as often as extension into the peritoneal cavity. appears as low signal intensity on T1-weighted images In up to 7% of cases, the abscess ruptures into the peri- and high signal intensity on T2-weighted images. After 12 toneum, causing peritonitis. Hepatic vein and inferior healing, the periphery of the abscess may calcify as a vena cava thrombosis secondary to amebic liver abscess thin, round ring. 13 have also been described. Occasionally, patients have a A chest radiograph abnormality will be observed more chronic presentation with months of fever, weight in approximately 50% of patients with an amebic liver loss, and abdominal pain with or without hepatomegaly. abscess, most commonly elevation of the right hemidia- No differences in clinical manifestations or radiographic phragm. This finding does not necessarily signal pulmo- findings in HIV-infected individuals as compared with nary involvement in the infection. seronegative individuals with liver abscess have been On gallium citrate and technetium-labeled sulfur 11 observed. Uncommonly, patients with amebic hepatic colloid radionuclide liver scans, amebic abscesses are abscesses may also have localized colonic infection result- “cold” (with a bright rim in some cases), whereas pyo- ing in a mass of granulation tissue forming an ameboma, genic abscesses are “hot.”15 14 which may mimic colon cancer. Patients with secondary Serial imaging is generally not helpful since lesions cardiac or pulmonary involvement may present with may appear to increase in size or number on ultrasound