Some etiologic concepts of actinomycosis of the greater omentum.

Since 1955, 33 patients with actinomycosis were treated at the University Hospital, Saskatoon, Sixty-seven per cent of the lesions involved the cervicofacial region; 24 per cent, the abdomen, and 9 per cent, the thorax. Trauma, inflammation or immunosuppression may have been partly responsible for the infection in 14 of the patients. Follow-up data were available for 21 patients. One of these patients died of thoracic actinomycosis, having received immunosuppressive therapy for leukemia. The others progressed well after treatment. In one patient with intra-abdominal actinomycosis, the disease was confined to the greater omentum and was apparently unrelated to the gastrointestinal or genitourinary tracts. He recovered after excision of the greater omentum and large dosages of penicillin. A search of the literature reveals that other reports on seemingly isolated intra-abdominal actinomycosis describe disease adjacent to hollow organs which required their removal. Immunologic studies demonstrated that a saline suspension of Actinomyces israelii was capable of inhibiting phytohemagglutinin stimulation of both the lymphocytes of the patient and of those of three normal donors. This may play a part in the progression of the disease.