EXTRA INTESTINAL LESIONS

DR . SANDHYA MISHRA

ENTAMOEBA HISTOLYTICA

METASTATIC LESIONS IN LIVER

Hepatic Amoebiasis(Amoebic Liver Abscess)

Incidence---- . 2-10 % .Less common in women and rare in children. .Develop any time during intestinal infection..Generally appears when the intestinal

symptoms have subsided..In the majority of cases, the hepatic

complication appears after about 1-3 months of the disappearance of the dysentery attack.

Genesis of Hepatic Lesions----- . The trophozoites are carried as emboli by the

radicles of the portal vein from the base of an amoebic ulcer in the large intestine (caecum and the ascending colon).

.Capillary system of the liver acts as an filter and hold these parasites.

.Trophozoites multiply in large no. and their cytolytic action continues.

.Local accumulation –obstruction to the circulation— thrombosis of the portal venules – anaemic nerosis of the surrounding liver cells.

.Primary lesion – focal necrosis of the liver cells (starting point of liver abscess)--- destruction continues in concentric layers.

.First necrotic material consists of a solid slough ----- centre liquefies by cytolytic action -----liquefaction extends radially.

.Big sized abscess is formed by coalescence of these miliary abscesses.

MACROSCOPIC PATHOLOGY

.Generally confined to the postero-superior surface of the right lobe.

.To the naked eye, the appearance of the abscess area is reddish brown in colour with a semifluid or grumous consistency.

.The wall of the abscess cavity is ragged and shaggy in appearance and is formed by the necrotic liver tissues which gradually merge into the healthy zones with an intervening zone of hyperaemia

MICROSCOPIC PATHOLOGY

Three zones can be differentiated:

1.)A central zone of cytolysed granular material with no amoeba.

2.)An intermediate zone consisting of degenerated liver cells, a few leucocytes,connective tissue cells,red blood cells and an occasional trophozoites seen.

3.)Aperipheral zone consisting of congested capillaries with varying degrees of necrosis of liver cells. The amoeba can be seen multiplying in this area and invading the adjoining healthy liver tissue.

Pus of Liver Abscess---.Pus is a mixture of sloughed liver tissue and

blood..It is chocolate brown in colour and thick in

consistency (ANCHOVY –SAUCE PUS)..Smell- offensive.Bacteriologically sterile..Microscopically– reveals degenerated liver

cells ,a few red blood cells and occasional leucocytes.

Clinical features of Amoebic Liver Abscess .Onset is insidious. .Pain and tenderness in the right hypochondrium . .Pain is sometimes reffered to the right acromial

region..Dry cough may often be associated..Occasionally the pain is reffered to the lower abdomen

or the right iliac region..Fever- A slight rise of temp. in the evening which later

becomes quotidian and takes on a hectic character..The patient becomes emaciated.

.EXAMINATION------

. The lower border of the liver is palpable below the coastal margin and is tender. Liver dullness may extend upwards.

.The movement of the right side of chest during respiration is diminished.

.Occasionally, there may be a bulging of the parieties, indicating the pointing of the abscess.

.The left lobe of liver may undergo a compensatory hypertrophy in a very big abscess.

Lung signs- these are due to the collapse of the right lung base caused by the growing liver abscess.

Apical impulse- this may be displace upwards and laterally by a large abscess.

Intestinal symptoms are absent. On abdominal palpation, areas of thickening of the bowel with tenderness may be present.

COURSE AND TERMINATION OF LIVER ABSCESS

METASTATIC LESIONS IN OTHER ORGANS

LABORATORY DIAGNOSIS OF AMOEBIASIS

Diagnosis of Intestinal Amoebiasis

A.)Symptomatic Group—cases of Acute Amoebic Dysentery.

1.)Examination of stool----

a.)Macroscopic Appearance-.Dark brown offensive semi-fluid stool..Acid in reaction.Admixed with blood,mucus and much faecal

matter..It does not adhere to the container.

b.)Microscopic appearance—.The cellular exudate is scanty and consists of only the nuclear

masses (“pyknotic bodies”) of a few pus cells, macrophages and epithelial cells.

.The red blood cells are clumped and are reddish –yellow or yellowish- green in colour.

.Presence of Charcot- Leyden crystals.

C.)Demonstration of E.histolytica (by examining an unstained preparation microscopically)—

.Fresh stool unmixed with any antiseptic or urine s/b examined.

.In acute cases ,the amoebic trophozoites can easily be recognised by their characteristic movement and the presence of red blood cells.

.Iodine stained preparations is used to demonstrate cysts and dead trophozoites.

.The trophozoite of E.histolytica stains yellow to light brown.

.Nucleus is clearly visible with a central karyosome.

.The cytoplasm of cystic stage shows smooth and hyaline appearance.

. Nuclear chromatin and karyosome appear bright yellow, glycogen mass stain golden brown and chromatid bars are not stained.

.Trichome stain is used to demonstrate intracellular features of both trophozoite and cysts.

.

CYST IN IODINE STAINED PREPARATION

2.)Examination of blood --- shows moderate leucocytosis.

3.)Serological Test--- .In early cases, it is always negative..It becomes positive only in invasive

amoebiasis..Test used are---IHA, Latex agglutination test,

ELISA.

.

B.)ASYMPTOMATIC GROUP- Cyst- passers or cyst – carriers.

1.)Examination of stool---a.)Microscopic Examination---

i)A natural stool for cysts.ii) A smear prepared by concentration method(for cysts).iii)A purged stool obtained after a saline cathartic (motile

trophozoite and cysts),iv)The material collected by the use of sigmoidoscope

(trophozoite) when there are visible lesions in the sigmoido-rectal area.

.Three consecutive stool sample s/b examined for detection of cyst as excretion of cyst in stool is often intermittent.

b.)Cultural examination– stool negative microscopically, when cultured ,have on various occasions shown the presence of parasites. Robinson’s culture media and NIH polyxenic culture media are now available for culture of the stool for isolation of amoeba. Culture is not a routine diagnostic procedure.

c.)Animal inoculation—Not used now a days.

2.)Blood picture- not characteristic.

3.)Serological Test—These cases are seronegative.

MOLECULAR DIAGNOSIS.Recently ,DNA probes and Radioimmunoassay

have been used to detect E.histolytica in stool.It is rapid and specific method.

DIAGNOSIS OF HEPATIC AMOEBIASIS

1.)Diagnostic Aspiration –.The aspirated pus may be examined for the

demonstration of trophic forms of E. histolytica. 2.)Liver Biopsy-- .Trophic forms may be demonstrated in

specimens of liver biopsy taken from cases of miliary amoebic hepatic abscess.

3.)Examination of stool—.Cysts of E.histolytica are present in less than

15% cases of Amoebic liver abscess.

4.)Examination of Blood—.Leucocytosis, varying from 15,000- 30,000 /mm3 of blood..DLC shows neutrophil granulocytes to be 70-75%..LFT show raised ALP and S.G.O.T level.5.)Serological tests—(It is now possible to get pure and specific antigen from the

trophozoites of E.histolytica grown in an axenic medium)..Used for detection of specific antibody and mainly useful in

diagnosis of extra- intestinal amoebiasis..LAT, IHA,GD,IFA,ELISA may be used..LAT is fairly and frequently used.. Serological tests are virtually always positive in hepatic

abscess,but only about 85% positive in cases of dysentery..RIA and CCIE have also been used in cases of amoebiasis.

6.) Intradermal Test—.In an infected individual injection of 0.1 ml of an

antigen prepared from cultures of E. histolytica produces at the site of injection an erythema which manifest after 3 hrs. ,reaching a max. (9-10 cm in dia.) after 20-24 hrs. and disappearing in another 24-48 hrs.

7.)Radiological examination—.Right dome of diaphragm situated at a higher level..Sometimes there may be tenting of the diaphragm

because of basal pleurisy.

8.)Radio-isotope tracing of liver— .Hepatic photoscan has been introduced to

locate the space occupying lesion in the liver..I 131 labelled Rose Bengal as the tracer agent,

observed an area of focal filling defect in amoebic abscess of liver.

9.)USG of upper abdomen, CT scan of liver or MRI scan also used for detection of amoebic liver abscess.

Diagnosis of Pulmonary Amoebiasis

.Demonstration of trophozoite of E.histolytica in the sputum and by other immunological tests.

.The expectorated pus when examined fresh , may demonstrate the motile forms (trophozoites) of E.histolytica.

TREATMENT

1.)Tissue Amoebicides—

a.)In the intestinal wall, liver and other metastatic lesions-----Emetine and Dehydroemetine(administered parenterally).

b.)In the liver and lungs only--- Chloroquine.(1gm for 2 days followed by 5 gm daily for 3 weeks).

2.)Luminal Amoebicides—

a.)Direct acting luminal or contact amoebicides.i.)Halogenated hydroxyquinolones–

Di-iodohydroxyquinoline, iodochlorhydroxyquinolineii.)Dichloracetamide group, diloxanide(entamide).iii.)Antibiotics--Paromomycin

b.)Indirect- acting luminal amoebicides- Tetracycline.

3.) Both luminal and tissue amoebicides---. Metronidazole(750 mg TDS for 5-10 days) and

related compounds like Tinidazole (2gms OD for 3 days)and Nitroimidazole are administered orally

PROPHYLAXIS

1.)Personal Prophylaxis—i.)Boiled drinking waterii.)Protection of all food and drink from contamination by

flies, cockroaches and rats.iii.)Avoidance of use of raw vegetables and fruits.iv.)Personal cleanliness and elementary hygienic

conditions are to be observed while taking meals.2.)Community Prophylaxis—i.)Effective sanitary disposal of faeces.ii.)Protection of water supplies from faecal pollution.iii.)Avoidance of use of human excrement as fertiliser.iv.)Detection and isolation of carrier.

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