Helminthic pseudotumours of the bowel: thirty-four cases of helminthoma.

Human infestation with nematode worms of the superfamily Strongyloidea has been recorded from time to time to give rise to serious surgical complications. Worms of the genus Oesophagostomum are most frequently responsible. These are common parasites of ruminants, monkeys, and apes in which their histotropic phase is confined to the bowel wall and sometimes results in multiple inflammatory nodules. Man is an accidental host and it seems an abnormal one. The worm fails to return to the bowel lumen, migrates further and persists in the tissues. The commonest manifestation is a solitary tumour-like inflammatory mass or abscess (;helminthoma') in the ileocaecal region. The ileum, transverse and sigmoid colons are affected less commonly and the lesions are occasionally multiple. Patients may also present with abscesses of the abdominal wall. The clinical diagnosis is difficult, even at laparotomy. Carcinoma, appendicitis, ileocaecal tuberculosis are frequently simulated and unnecessary radical surgery is often the result, particularly in expatriate Europeans. In this communication 34 cases from Uganda are reviewed with emphasis on histopathology as responsibility for the correct diagnosis is likely to fall on pathologists. Three characteristic appearances are described and related to phases in the natural history of the disease. Current knowledge on parasitology is reviewed. The disease affects Africans as well as Europeans and it is anticipated that cases will be seen in those returning from the tropics.