Right lobe abscess can be classified into –

1. Abscess of the INFERIOR surface which can be sub-divided into:

1. 1. Junctional abscess.
   2. Abscess around the gall bladder area.
   3. Flank abscess.
   4. Posterior abscess (loin abscess).
   5. Huge inferior surface abscess of the whole right lobe enlarging forwards.
   6. Huge inferior surface abscess of the right lobe enlarging backwards.
   7. "Pre-rupture" syndrome produced by right lobe abscess.
   8. Ruptured inferior surface abscess presenting as an acute abdomen.

1. Abscess of LATERAL surface.
2. Abscess of the ANTERIOR Surface above the right level of the costal margin and underlying the right lower rib cage.
3. INTRAHEPATIC abscess.
4. Abscess in the "BARE AREA".
5. Abscess of the SUPERIOR surface which can be sub-divided into:

1. 1. Deep seated abscess of the superior surface.
   2. Superficial abscess of the superior surface.
   3. Superior surface abscess of the junctional area.
   4. Rupture of superior surface abscess presenting as "acute abdomen".
   5. Pleuropulmonary amoebiasis of the right side.

The above classification is based on my experience of two hundred cases of amoebic liver abscess seen and followed up at the nuclear medicine department of J.J. Hospital, Bombay 8 and at Jaslok Hospital and Research Centre, Bombay 26 (Table I).

TABLE I

Following are the descriptions of clear cut syndromes often seen in practice. At other times, at the bed side, one cannot go beyond localising the abscess e.g. to the right lobe – superior or inferior surface. Again, it may not be possible to palpate the liver properly in case of inferior surface abscess due to marked tenderness and guarding of the local muscles.

1. Abscess of the inferior surface

1. Junctional abscess. I consider a junctional abscess as one where the cold area is seen on the liver scan in the right lobe at its junction with the left lobe.^1,2 Actually this abscess is in that part of the right lobe which, based on arterial blood supply and accompanying bile ducts, is the medial part of the left lobe. It is likely that the quadrate lobe is the site of the affection in these cases. This abscess needs special nomenclature since it produces a typical swelling when present on the inferior surface of the liver (Figs. 5 a,b). The swelling is seen in the right hypochondrium, but slightly more medial than the usual gall bladder swelling. Depending on the size of the abscess the swelling may bulge forwards, less or more in extent. Unlike a left lobe abscess where the lump is in the epigastrium and left hypochondrium, this abscess produces a swelling which does not extend beyond the midline of the epigastrium.
   It is important to recognise this swelling because it can be confused with the swelling of the gall bladder. This is one abscess where ¹³¹ I Rose Bengal or ^99m Tc Hida scan will give more information that ^99m Tc sulphur colloid scan. Thus, after the cold area is seen, if in a delayed scan the gall bladder can be visualised, one can be sure of dealing with a liver abscess and not a gall bladder swelling³ (Figs. 6 a,b).
   Gajraj⁴ has observed that often in cases of amoebic liver abscess, the gall bladder does not fill up as seen in repeat ¹³¹I Rose Bengal liver scan. In my experience, the gall bladder is often visualised after 2-3 hours or even later.³ The delay occurs probably due to cholestasis which often occurs in these cases.
   In one of my cases , the liver scan taken after two and a half hours did not show filling of the gall bladder (Fig. 7). We could not repeat scans later because of a short vacation in the department. In this patient, I.V. cholecystography was attempted. No dye was seen in the gall bladder upto 6 hours.
   After 24 hours, when a barium meal study was being done, the gall bladder was seen filled up (Fig. 8). Since the gall bladder was not visualised as early as in other cases, there was a slight suspicion regarding the etiology of the lump. At laparotomy, the swelling was confirmed to be a junctional amoebic liver abscess (Fig 9). It had pushed the gall bladder backwards. This was the only junctional abscess in our series which was not aspirated. Figure 10 shows another junctional abscess at the operation table.
   Junctional abscess (like left lobe abscess) is NOT seen in the right lateral view of the liver scan. (Abscesses located in other parts of the right lobe are always seen in the right lateral view).
   Laparascopy is another very helpful investigation in such cases. Then one is able to see a normal gall bladder and an amoebic abscess in the right lobe adjoining the falciform ligament.⁵
   A junctional abscess can be aspirated easily per abdomen (Fig. 11). In my series of fourteen cases tapped per abdomen, there has not been a single mishap.
2. Abscess around the gall bladder area. (Figs. 12a,b,c,d)
   Although this presents like a junctional abscess, the swelling is slightly more lateral in position. However, in contrast to junctional abscess, all abscesses around the gall bladder (except the one medial to the gall bladder ) are always visualised in the right lateral view of the liver scan. Also like junctional abscess at this site can closely stimulate a gall bladder swelling. (Figs. 12a,b,c,d)show ¹³¹I Rose Bengal liver scan of amoebic liver abscesses just medial and lateral to, above and around, the gall bladder.
3. Flank abscess. Figure 13 shows a typical bulge produced by an amoebic abscess in the flank. This is one of the best examples of a superficial abscess of the inferior surface arising from the lateral edge.⁶ I have seen five such patients.
   Whenever a patient complains of fever and pain localised to the right flank, he must be examined in the standing position with the area facing very good light. The swelling is best seen when the patient takes deep breaths.
   Although the lump is too lateral to be a gall bladder, ¹³¹I Rose Bengal scan may be resorted to so that the gall bladder can be visualised (Figs. 14 a,b). In two of our five cases, the cold area was so ill defined that one could not make a definite diagnosis on liver scan alone. Peritoneoscopy had to be done in both cases to confirm the diagnosis.
   A positive I.H.A. test in a very high dilution would be an asset in these cases.
   A therapeutic tap relieves the patient dramatically (Fig 15). The earlier it is done, the better. Such abscesses, though small, often rupture into the peritoneal cavity.
4. Posterior abscess (loin abscess). In patients with postero-inferior and dead posterior abscesses, tenderness is elicited in the loin, often around the area of the renal angle. When large in size, these abscesses produce a bulge in the right loin (Fig. 16) and mimic a cold abscess or a perinephric abscess.
   Clinically, a "cold abscess" (from tuberculous spine) is excluded by the absence of acute pain and tenderness.
   From the time hepatic scintigraphy has been adopted more routinely at various centres and the importance of studying more than one view (anterior and right lateral) has been realised, the diagnosis of posterior surface amoebic liver abscess is made more often. ^7,8 Even when the anterior view is normal, a right lateral view may show a cold area on the posterior surface. This may be dead posterior or postero-inferior (Figs 17, 18, 19). Majority of them are of the latter variety.
   Surprisingly, we have seen radiological changes in the right dome of the diaphragm produced by a "dead posterior" abscess. In our opinion, these changes are due to the anatomical relation of this area to the diaphragm.
   In our experience, the best position to tap the posterior abscess is in the posterior scapular line with the patient leaning forward on the cardiac table rest (Fig 20). In the past, these abscesses were drained from the mid axillary line. In this method the abscess would not be drained efficiently and completely.
5. Huge inferior surface abscess of the whole right lobe enlarging forwards. Sometimes an amoebic abscess may involve the whole inferior surface of the right lobe (Fig 21) In such a case, there is a huge downward and forward enlargement of the whole right lobe but the epigastrium may be empty (Fig 22). The right lobe enlarges in such a manner that the all bladder swelling does not pose a problem as a differential diagnosis Liver scan often shows a huge cold area in the lower half or two thirds of the right lobe (Figs 23 a,b,c) Serological tests, if available, would be useful in this situation.
6. Huge inferior surface abscess of the right lobe enlarging backwards. These are the most difficult cases to diagnose. Since the abscess expands backwards, the swelling cannot be felt very well. There is, therefore, only a vague ill-defined lump felt in the upper abdomen. One cannot be sure whether the lump is arising from the liver or surrounding organs like pancreas, kidney or suprarenal gland etc. Short of peritoneoscopy, only a positive history of dysentery, alcoholism, pain and fever may be useful. However, even if liver scan shows a cold area on the inferior surface, if peritoneoscopy is not available, barium meal of the stomach and l.V. pyelography must be done before attempting a diagnostic tap. This is because extrahepatic lumps can often produce cold areas on liver scan in the lower part of the liver. Serological tests for amoebiasis, when available, must also be carried out.
7. "Pre-rupture" syndrome produced by right lobe abscess. These patients present as "acute abdomen" with severe pain, tenderness, rigidity, guarding and a doubtful tender hepatomegaly. Sometimes they have a subacute onset with pain, tenderness, distension and other signs of paralytic ileus. Often on laparotomy the surgeon neither finds a ruptured liver abscess nor free pus in the peritoneal cavity. According to Ramachandran et al⁹ these patients, if diagnosed properly, would respond very well to closed aspiration and medical treatment. According to them there are two valuable points which help in picking up such cases-(i) occasional movement of the abdominal wall during respiration, (ii) disappearance, even momentarily of the rigidity and guarding of the abdomen while talking to the patient with the purpose of gaining his confidence.
   The phenomenon of "pre-rupture" is almost invariably seen in abscesses of the right lobe. It is more common with superficial abscesses. Flimsy fibrinous adhesions between the visceral and the parietal layers of the peritoneum are often seen over the abscess. This syndrome is probably due to the fact that in a superficial abscess a larger area of the liver capsule is stretched than that in the usual deeper abscesses. The disappearance of abdominal manifestations after closed aspiration in such patients, is probably due to the reduction in the stretch of the peritoneum over the site of the abscess .⁴
8. Ruptured inferior surface abscess presenting as an acute abdomen. Sudden rupture of the amoebic abscess (Fig. 24) is followed by soiling of the peritoneum with amoebic pus. This results in peritonitis^10-11 and the patient presents with acute abdomen. Laparotomy has to be done in all such cases. (This has been discussed in detail elsewhere.)

II. Abscess of the lateral surface
Usually this abscess causes a generalised bulge of the infra-axillary area (Figs. 25 a,b) and is easy to diagnose. There is superadded oedema of the intercostal spaces. Figure 26 shows such a swelling after 1200 ml. of pus was removed on the previous night. On liver scan, majority of such abscesses are seen in postero-inferior area (Figs. 18 a,b).
Rarely a dead lateral abscess (Fig. 27) may be seen. These abscesses are very safe and do not rupture. More often they respond well to medical line of treatment and need not be tapped. However, if the response to medical treatment is poor, there should be no hesitation in putting a needle.

III. Abscess of the anterior surface above the level of costal margin and underlying the right lower rib cage.
The abscess is above the costal margin but it does not reach the superior surface to alter the right dome of the diaphragm. Clinically no lump is visible, but there is marked tenderness over the anterior part of the right lower chest. On liver scan, the cold area is seen on the dead anterior surface of the right lobe and is best appreciated in the right lateral view (Fig. 28). Tapping from the mid-axillary line is often futile. We have successfully tapped these abscesses from the anterior surface, sometimes under the guidance of a peritoneoscope (Fig. 29)

IV. Intrahepatic abscess
Cases of "amoebic hepatitis" are often referred to Nuclear Medicine Department to exclude amoebic abscess. While working in this department I have observed that the diagnosis of amoebic hepatitis is often made when the patient has intrahepatic abscess (Fig. 30) or an abscess of the inferior surface of the right lobe of the liver. Since these patients have symptoms of hepatic amoebiasis, radiologically a normal right dome of the diaphragm and a good therapeutic response to drug therapy without aspiration, the temptation to make a diagnosis of amoebic hepatitis is great in the absence of a liver scan.

V. Abscess in the "bare area"
Abscess in the "bare area" of the liver will generally present as pyrexia of unknown origin, till it leaks to cause perinephric suppuration.

Vl. Abscess of the superior surface

1. Deep seated abscess of the superior surface. Most text books describe the clinical picture of this type of amoebic liver abscess only. This is because it is one of the most common sites of amoebic liver abscess.discussed ^12-15 Although the picture has been earlier, a few points would need repetition.

1. Most often, the liver in these patients enlarges upwards. This can be confirmed by percussing the upper border of liver and visualising the elevated right dome on X-ray chest. Rarely the lower margin of the liver may not even be palpable.
   The elevation of the diaphragm, if generalised will be seen in the anterior view of X-ray chest, but if localised may only be seen in the lateral view (Figs. 31 a,b,c). Although many superior surface abscesses produce an elevation of the diaphragm with a smooth contour, haziness or irregularity of an elevated right dome is more diagnostic of such an abscess. I have often seen an elevated right dome due to a huge inferior surface abscess (Section V Fig. 3), where the lower margin of the right lobe was palpable 6-8 cms. below the costal margin and was very tender. Whether the elevation produced is due to "pressure" or some other cause, the contour of the right dome in such cases is often absolutely smooth.
   Then, pain in the shoulder or in the area of the trapezius or supraspinatus is the only leading symptom of the superior surface abscess. Markedly restricted movement of the right dome of the diaphragm rather than its elevation, as seen on fluoroscopy, is of greater significance in the diagnosis of superior surface abscess. (Minimal to moderate restriction of movement can often be present in inferior surface abscesses).
2. In diagnosis of superior surface right lobe amoebic abscess, a flat elevated diaphragm is more important than an elevated rounded diaphragm (Fig. 32). This flattened appearance is possibly due to obliteration of cardiophrenic and costophrenic angles.
   In our experience in the nuclear medicine department superior surface abscesses are more often supero-posterior (Figs. 33 a, b) than supero-anterior (Figs. 34 a, b).

2. Superficial abscess of the superior surface. Rarely a superficial superior surface abscess can occur without any elevation of the right dome of the diaphragm In two of my patients, even the scan did not show a clear cut cold area in the superior surface. This subject has been further discussed elsewhere. (Section V)
3. Superior surface abscess of the junctional area. Figure 35 shows a cold area produced by junctional abscess on the superior surface of the liver as seen on liver scan. We have seen four such cases. The left dome of the diaphragm was elevated in all of them. The importance of these abscesses is their tendency to rupture into the pericardium like the amoebic liver abscess of the left lobe. This, however, is based on my experience of a single case in the pre-scan days. This patient had symptoms of liver abscess and an elevated left dome of the diaphragm (Fig. 36). In the wards, the patient developed pericardial effusion, making the diagnosis of a left lobe amoebic liver abscess even more certain. On exploring, under local anaesthesia, surprisingly the left lobe was found to be normal. But when needling was done towards the junctional area (Fig. 37), typical chocolate coloured pus was aspirated. It may be noted that the right dome of the diaphragm was normal in this case. It is very important to note that like inferior surface junctional amoebic liver abscesses, these abscesses are also not seen in the right lateral view on the liver scan.
4. Rupture of superior surface abscess presenting as "acute abdomen". Occasionally, a superior surface amoebic liver abscess of the right lobe can rupture and present as acute abdomen. An elevated right dome of the diaphragm is the main sign to detect these cases pre-operatively.
5. Pleuropulmonary amoebiasis of the right side. It is important to note that a superior surface amoebic liver abscess of the right lobe may invade the right lung or pleura so quickly, that the patient presents with a picture of chest disease. This subject is discussed in a separate chapter.

References

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2. Kapoor, O P. and Mistry, C J. J. J. Group of Hospitals & Grant Med. Coll., 1978, 23, 88
3. Kapoor, O P. and Mahajan, U A, Paper read at XXXVlIlth Annual Conference of Association of Physicians of India, Bhopal, Jan. 1978.
4. Gajraj, A, Personal communication.
5. Kapoor, O P. Udwadia, T E, et al, Paper read at Ist Annual Conference of Society of Gastro intestinal Endoscopy of India, Bombay, lan. 1978.
6. Kapoor, O P. Paper read at International Conference on Advances in Internal Medicine, Bombay, lan 1978
7. Kapoor, O P. and Mistry, C I, Paper read at IXth Annual Conference of Society of Nuclear Medicine of India, Trivandrum, Oct. 1977.
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10. Archampong, E Q. Brit. J Surg., 1972, 59, 172.
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12. Beeson, P B. and McDermott, W. Text Book of Medicine, W B Saunders & Co, Philad., 1975.
13. Macleod, I, Davidson's Principles and Practice of Medicine, Churchill Livingstone, Edinburgh, 1974
14. Sherlock, Sheila, Diseases of the Liver and Biliary Svstem, Blackwell Scientific Publications, Oxford, 1975, 613.
15. De land, F B. and Wagner, H N. Atlas of Nuclear Medicine, W B Saunders & Co., Philad., 1972.