Isolated amoebic appendicitis.

Amoebiasis, a disease of worldwide distribution, is endemic in tropical countries with suboptimal sanitation facilities. Isolated amoebic appendicitis (IAA) is regarded as a rare manifestation of the disease globally. Because there are no defined clinical features that distinguish IAA from bacterial appendicitis, diagnosis is usually dependent on histopathological examination. A 9-year retrospective study was undertaken to investigate the clinicopathological aspects of IAA. The main complaints were fever and abdominal pain. None of the patients had dysentery. The pre-operative clinical diagnosis was acute appendicitis and acute abdomen in 13 and 8 patients, respectively. In all cases the intra-operative diagnosis was acute appendicitis. Gross pathological appraisal revealed peritonitis and perforation in 19 and 17 cases, respectively. Histopathological examination of these appendices demonstrated appendiceal ulceration, transmural mixed inflammation, haematophagous amoebic trophozoites and necrosis in all cases. Vascular pathology comprised venous and capillary luminal plugging (11 cases), necrotising small vessel vasculitis (11 cases), thrombophlebitis of medium sized veins (9 cases) and arteritis with associated thrombosis (1 case). Organising fibrinopurulent peritonitis was present in 19 cases. Two appendices that appeared normal macroscopically demonstrated ulceration and inflammation that were confined to the mucosa and submucosa. All of 18 patients who were treated with metronidazole survived without further surgery, while three patients who were untreated succumbed to the disease. Appendicectomy, accurate histopathological appraisal thereof and optimal, timely management of IAA were critical to the favourable outcome in the present study.