The abscesses vary enormously in size, some being no larger than a walnut while others may contain a quart or more of pus, exceptionally as much as a gallon. The pus is typically of a chocolate color and contains degenerated liver cells, granular débris and often haematoidin and Charcot-Leyden crystals. There is an absence of polymorphonuclears. It may however be creamy in color.
In Strong’s cases about 50% of the abscesses showed bacteria upon culturing, the organisms noted being staphylococci, streptococci, B. coli and B. pyocyaneus.
The walls of liver abscesses are rather shaggy and the amoebae are found deeply located.
It is probable that the necrotic process, set up by the amoebae, begins in the interlobular capillaries although it may at times begin within the lobule.
Microscopically, the necrotic abscess wall shows amoebae in its depths but necrosis of the surrounding tissue beyond the zone of the amoebae is noticeable which would suggest the elimination by the amoebae of some toxic substance. There is an absence of polymorphonuclear infiltration around the abscess.
Surrounding the abscess wall there is a zone of marked hyperaemia. Amoebae may be found in this area as well as in the abscess wall.
If the liver abscess is not treated by emetine or with this drug and some surgical procedure the tendency is for rupture to occur and Cyr’s statistics show that of 159 cases rupture occurred as follows: lungs 59, pleural cavity 31, peritoneal cavity 39, intestines 8, stomach 8, vena cava 3, kidneys 2, bile ducts 4, pericardium 1 and externally 2.
Symptomatology
Although the statistics would indicate that a history of amoebic dysentery has been obtained in only from 60 to 90% of cases of liver abscess, yet, when we consider that amoebic lesions of the large intestines have been frequently noted at autopsy in those who had never shown symptoms of dysentery during life, we are forced to believe that amoebic lesions of the appendix or large intestines are necessary factors in the production of liver abscess. Consequently, a history of amoebic dysentery is one of the most important points to consider in the making of a diagnosis of tropical liver abscess.
Tropical Liver.—There is also much evidence to be obtained from statistics and otherwise to support the view that the amoebic infection of the liver is only possible in a person whose liver has been functionally impaired. To this condition the designation tropical congestion of the liver or simply tropical liver has been applied. There is much to support the view that, in the tropics, the intestines and liver take the place of the thoracic organs in being subject to congestion. In temperate climates excesses and exposure to debilitating influences result in coryza or pneumonia. In the tropics we have diarrhoea and congestion of the liver. Tropical liver is recognized by vague digestive troubles, high-colored urine, loss of energy, irritability, with a sensation of fullness in the region of the liver which is generally described by the patient’s statement that he feels his liver. There may be pain referred to the right shoulder and the liver may be tender on palpation.