[Tumoral form of abdominal and retroperitoneal actinomycosis].

We present a case of abdominal and retroperitoneal actinomycosis, clinicaly evidenced by a large tumor in the left inferior abdominal quadrant, in a 72-year-old male. Following clinical and laboratory investigations (imaging), strong suspicion of a left colon neoplasm was raised. Surgery consisted in an exploratory laparotomy and multiple biopsies of the great omentum and retroperitoneal space, the case being considered above the therapeutic resources. Histopathological diagnosis was a surprise by setting actinomycotic etiologies and enabled the establishment of a proper antibiotic treatment, followed by a favorable evolution. Postoperative follow-up revealed disappearance of lesions and healing.