Abdominal actinomycosis.

Purpose: Actinomyces israelii are normal inhabitants in the oral cavity and upper intestinal tract of humans. They rarely cause disease and are seldom reported as pathogens. As a pathogen it causes fistulas, sinuses, and may appear as an abdominal mass and/or abscess. The abdominal mass can masquerade as a malignant process that is very difficult to differentiate, often requiring surgical intervention with resection. Because of difficulty in making a preoperative diagnosis, we undertook this review to determine if all patients require surgical intervention and whether other adjunctive modalities may improve preoperative diagnosis.
Methods: We report two patients with abdominal actinomycosis, one affecting the sigmoid colon and the other the retroperitoneum, iliac crest region. Both simulated a malignant process and required operations for diagnosis and treatment.
Results: As reported, actinomycotic abdominal masses and strictures can be treated by penicillin alone. Long-term medical treatment seems to be very successful and avoids surgical resection. The difficulty is obtaining a definitive diagnosis.
Conclusion: The computed tomographic scan is the most helpful diagnostic modality. Appearance of abdominal actinomycosis is usually a contrast enhancing multicystic lesion as was found in these two patients. Needle aspiration cytology can be fairly accurate in obtaining the diagnosis and is recommended for suspicious lesions.