Amoebic liver abscess of the left lobe is relatively less common than the right lobe.^1-3 Rogers recorded that, of the amoebic liver abscess cases in European hospitals, left lobe formed 11.9%, while in the Indian medical college hospitals the incidence was 18.3%. According to Manson-Bahr, only 10-15% of amoebic liver abscess occur in the left lobe.⁴ In our series we found an incidence of 12%.
Table I shows incidence of the left lobe abscess in other series.

TABLE I

Based on the arterial supply and the accompanying hepatic ducts, the anatomical left lobe is the lateral segment of the left lobe. It is situated in the epigastrium and left subcostal area. Anteriorly it is partly covered by the left costal margin and only a part of it presents itself to the clinician for palpation in the epigastrium. Its superior surface is closely related to the central tendinous part of the diaphragm and part of the left cusp, which separates it from the pericardium, heart, left pleural cavity and the left lung. Its inferior surface is related to the stomach, duodenum and the transverse colon. It is closely related to five potential spaces into which pus may collect in the event of rupture of amoebic abscess of the left lobe. These are: (1) the pericardial sac, (2) the left pleural cavity, (3) the left subphrenic space, (4) the general peritoneal cavity and (5) the lesser sac of the peritoneum.
An amoebic abscess of the left lobe may form, either near its superior, or inferior surface. Because of the potentially greater space in the left subcostal area, an abscess near the superior surface may remain occult or its symptoms and signs may remain relatively vague until it attains a significant size.¹¹ On the other hand if the abscess is superficial, it may rupture into the thorax, before attaining a large size. The clinical picture may then be dominated completely by symptoms and signs of the complications resulting from the rupture of the abscess with little or no evidence of the existence of the abscess. As the abdominal cavity offers less resistance, downward extension is seen more frequently in a left lobe abscess.⁴ An abscess in the inferior part of the lobe may devour the substance of the liver and (because of the small mass of the left lobe) quickly reach the anterior or inferior surface, making rupture imminent.
Therefore, the incidence of secondary involvement of the adjoining organs and other complications is higher in cases involving the left lobe rather than the right.⁴
On account of the above-mentioned anatomical peculiarities, amoebic abscess of the left lobe produces clinical syndromes which are not only distinct but also of varied nature, as compared to the right lobe abscess in which clinical features are more constant.⁹ Paul¹¹ was one of the earliest to recognise this fact.
Syndromes produced by amoebic liver abscess of the left lobe are described below. It must be kept in mind that although the abscess can occur predominantly in the superior or inferior surface, an abscess of the left lobe often involves both the surfaces (Fig. 56) and thus produces a combined picture.¹² Also when the abscess is in the superior surface, the rest of the left lobe is quite often enlarged so as to be palpable in the epigastrium. A co-existing abscess in the right lobe is also common and should not be overlooked. This has been stressed in the chapter on multiple amoebic liver abscesses.
Clinical syndromes produced by left lobe abscess can be classified into-

"Clinical syndromes" produced by an inferior surface abscess of the left lobe

1. Enlarged tender left lobe.
2. Small superficial lump in an enlarged left lobe.
3. Large intrahepatic abscess producing a big lump in the epigastrium.
4. Rupture of abscess with localization.
5. Rupture of abscess with generalized peritonitis.
6. Abscess of the caudate lobe.

II. "Clinical syndromes" produced by superior surface abscess of the left lobe

1. Uncomplicated superior surface abscess (U.S.S.S.L.L.L.A.L.A. syndrome).
2. Complicated superior surface abscess whiz may present as-

1. Amoebic pericarditis.
2. Left pleuropulmonary amoebiasis.
3. Combination of left pleuropulmonar amoebiasis and amoebic pericarditis.

I. "Clinical syndromes" produced by an inferior surface abscess of the left lobe

1. Enlarged tender left lobe. An enlarged tender left lobe is palpable in the epigastrium and the left hypochondrium, which moves very well with respiration (Fig. 57). No lump is seen or palpated. Patient complains of upper abdominal pain or discomfort of varying intensity. Pain is aggravated by respiratory movements or Iying in left lateral position. Liver scan shows a cold area on the inferior surface of the left lobe (Fig. 58). Radiological investigations may not provide any further information of value, but serological tests and peritoneoscopy would help. If necessary, aspiration can be done safely per abdomen.
2. Small superficial lump in an enlarged left lobe. These patients have a soft tender lump within the enlarged left lobe (Fig. 59). The lump may be palpable in the epigastrium or brought out from under the left costal margin by deep inspiration or by turning the patient to a right lateral positioned. This lump moves well with respiration, as the abscess is well localised within the liver unlike one in which rupture is imminent.¹¹ Liver scan shows a cold area on the inferior surface of the left lobe (Fig. 60). However, the radiological investigations may be negative. Serological tests and peritoneoscopy would also help in the diagnosis. Since these lumps can always rupture, they should all be aspirated per abdomen (Fig. 59)
3. Large intrahepatic abscess producing a big lump in epigastrium. The abscess is sufficiently large in size to produce a space-occupying mass in the epigastric and left subcostal region (Figs. 61 a,b). The entire left lobe may be destroyed and replaced by the abscess.⁹ The lump is tender and smooth but still moves with respiration. It causes compression or vascular congestion of the adjoining organs causing additional symptoms such as nausea, vomiting and diarrhoea and signs like prominent epigastric veins and obliteration of Traube's space. Some of these abscesses also extend in a backward and upward direction. Such patients may complain of referred pain at the tip of the left shoulder due to irritation of the left hemidiaphragm.¹⁴ Low dysphagia due to displacement of intra-abdominal portion of the oesophagus has also been reported.¹⁴ If the abscess extends mainly backwards, it appears to be deep seated on palpation. Such cases have been wrongly diagnosed as perigastric abscess, left perirenal abscess or rolled up omentum.^2,4 A case in which the lump transmitted the pulsations of aorta and was initially misdiagnosed as aneurysm of the abdominal aorta, has been recorded.² In chronic or partially treated cases, signs of inflammation may be absent and the lump may be firm and irregular akin to hepatic carcinoma¹⁴ Apart from liver scan (Fig. 62), peritoneoscopy and radiological investigations also may furnish diagnostic information in this group of patients.
   Our policy is to aspirate all the huge left lobe abscesses per abdomen as early as possible. This is because rupture is more likely in the left lobe abscess. For the same reason, in the past, they were submitted to open surgery. Many authorities are now convinced that tapping per abdomen is quite a "safe" procedure.
4. Rupture of abscess with localization. Sometimes the abscess leaks into the peritoneal cavity but gets walled off quickly thus forming a localised abscess.¹⁴ Depending upon the site of leakage, the abscess may get localised to the left anterior subphrenic space, left posterior subphrenic space or the left infrahepatic region.¹⁴ The abscess may communicate with the lesser sac without soiling the peritoneal cavity.⁹ it may form adhesions with diaphragm, anterior abdominal wall, stomach, duodenum, transverse colon, omentum, etc.⁹
   The physical signs depend on the site of localisation. A tender irregular lump (Fig. 63) is palpable in the epigastrium and left hypochondrium, sometimes extending towards the umbilicus. The movements with respiration are markedly restricted due to adhesions^11,14 Radiological signs are of great help in ascertaining the size and site of the abscess. This would be complemented by peritoneoscopy and liver scan. Serological tests, if positive in high titre, are very useful.
   Though some of these patients would need open drainage, many of them can be aspirated even at this stage with good results.
5. Rupture of abscess with generalised peritonitis. This results in acute abdomen which has already been discussed elsewhere. Laparotomy has always to be performed in these cases. The picture of pre-rupture syndrome is not seen in left lobe abscesses .
6. Abscess of the caudate lobe. As explained earlier this is the medial part of the left lobe. An abscess in this area is generally silent, till it leaks into the lesser sac, when it produces a painful epigastric swelling.
   A number of radiological signs have been described in left lobe amoebic abscess.^15-17 Following are the radiological features which may be present in large "inferior" surface abscesses:

1. Plain X-ray of the abdomen may show-

1. soft tissue mass in the epigastrium and left hypochondrium¹⁴ (Fig. 64).
2. downward displacement of the transverse colon (Fig. 65).

2. Barium meal studies of the stomach and duodenum may show the following appearances:

1. a well-defined concave (extrinsic pressured defect on the lesser Curvature² (Fig. 66).
2. (a localised crescenteric deformity of the lesser curvature (Fig. 67).
3. stretching and rounding of the lesser curvature around the mass with its displacement to the left (Fig. 68).
4. lateral view of the barium filled stomach may show posterior displacement of the stomach (Fig. 69) with or without indentation of the anterior surface producing a sickle-like appearances⁹ (Fig. 70).
5. forward displacement of the stomach.⁹
6. downward displacement of the duodenal bulb and medial displacement of the second part of the duodenum¹⁸(Fig. 70).

The following three signs on plain X-ray or barium meal study are usually seen with superior surface abscess but may also be seen in a large inferior surface abscess.

1. downward displacement of the cardia of the stomach ^12,18
2. a filling defect in the fundus of the stomach¹⁴ (due to extrinsic pressure).
3. elongation and posterior displacement of intra-abdominal portion of the oesophagus.¹⁴

3. Barium enema may show downward and forward displacement of the splenic flexure of the colon.⁵
4. X-ray chest is usually normal. But the following findings may be noted:

1. Elevation of the right dome of the diaphragm may be seen in cases of left lobe abscess. In the author's experience, this is always due to a co-existing right lobe abscess.¹¹ Other causes like generalised hepatic congestion¹or diffuse amoebic hepatitis¹⁹ are highly unlikely and were mentioned formerly, when liver scans were not available.
2. Elevation of the left dome of the diaphragm -This occurs more often in the case of superior surface abscess due to direct pressure of the expanding lesion. However, we have found this sign to be present even in case of inferior surface abscess.¹⁶ The likely mechanisms for the elevation in the latter cases are:

1. upward displacement and distension of the stomach compressed by an enlarged left lobe.
2. upward displacement of the loops of the splenic flexure.
3. adhesions of the loops of the colon following a leak from the abscess producing partial obstruction and distension (Figs. 72 a,b).
4. lastly as in the case of the right lobe, rarely the left dome gets elevated by a huge inferior surface abscess of the left lobe (Fig. 73).

Role of peritoneoscopy in the diagnosis
In groups 1 and 2 liver scan often helps in the diagnosis. But from group 3 onwards, liver scan is a poor investigation to differentiate a left lobe liver abscess from other upper abdominal lumps. In these cases the cold area seen in the left lobe could be due to an extrahepatic mass. So often have these mistakes been made that , in the author's opinion, peritoneoscopy in such patients is much more superior and informative than a liver scan. If both investigations are available, both must be done.²⁰ For example, though peritoneoscopy may show a huge inferior surface abscess of the left lobe, a second abscess in the posterior portion of the right lobe may be missed. The latter would also be picked up on a liver scan.
Clinical syndromes produced by superior surface abscess of the left lobe have been discussed in the next few chapters.

References

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