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Museum of Pathology

AMOEBIC ABSCESSES OF BRAIN

AMOEBIC ABSCESSES OF BRAIN

Clinical History

This 44 year old man presented with a 6 week history of very frequent diarrhoea of sudden onset. There was no associated pain. There was weight loss of 3 stone over the next week, and 2 days prior to admission, the patient had passed bright blood rectally. On examination: Sigmoidoscopy revealed acutely inflamed bowel. Staph. aureus was cultured. The provisional diagnosis was ulcerative colitis from a biopsy obtained at the time of sigmoidoscopy. Large bowel mucosa shows a little non-specific acute inflammation at the top of the mucosal folds. There is no evidence in these sections of ulceration. This is consistent with a diagnosis of early ulcerative colitis. As there was no response to conservative measures, colectomy was performed. Post-operatively, there was a lessening of fever, but no other improvement. Biopsy report on operative specimen showed definite evidence of amoebic colitis with presence of vegetative organisms. Examination of slime from the large bowel remnant revealed the presence of motile amoeba histolytica. Direct fresh blood transfusions were given because of thrombocytopenia. White cell count at this stage rose to 77,000 (neutrophilia) and platelet count dropped to 10,000/cmm. There was steady deterioration, the patient becoming jaundiced and semi-comatose. Death occurred 4 days post-operatively.

Pathology

There are 2 specimens. The first is of both cerebral hemispheres sliced coronally through the basal ganglia, the cut surface being displayed and viewed anteriorly. In the left hemispheres, two zones of haemorrhagic necrosis are present involving both white and grey matter. One area is adjacent to the median fissure, 2 cm from vertax and is 2 cm in maximum diameter. The lesion shows a greyish granular necrosis with multiple, small associated haemorrhages. The second lesion is 2.5 cm in diameter and more laterally situated. Here there has been fragmentation of necrotic brain. Smaller lesions 1-3 mm in diameter are also visible in both hemispheres in both grey and white matter (1-3 mm) and sectioned vessels appear more obvious than usual. The second specimen consists of a further coronally sliced section of cerebrum and a portion of horizontally sliced cerebellum. In each case the cut surfaces are displayed. Similar lesions to those in the previous specimen are present, some being placed beneath the surface. These lesions are bulging the surface slightly and there is thickening of the overlying meninges. There is some greenish discolouration in white matter adjacent to the necrotic areas. These are examples of amoebic abscesses of brain. At necropsy, a large abscess of liver had ruptured into the interior vena cava and many pulmonary abscesses were present also.