Figure 1: Axial computed tomography image show a soft tissue mass, located between left psoas muscle and lateral abdominal wall. The lesion partially surrounds the sigmoid colon (A). Contrast enhanced CT arterial (B) and venous (C) phase show marked heterogeneous involvement.

Figure 2: Arrow indicates the location of removed mass. It was over sigmoid colon (SC) and lateral abdominal wall (LAW).

Figure 3a: A colony of actinomyces and mixed inflammatory response at the periphery which include histiyocytes, lymphocytes, plasmocytes, eosinophils and neutrophils. ( H&E, original magnification x100 )

Figure 3b: Colony of filamentous microorganisms stain black with Grocott’s methenamin silver conventional staining method ( magnification x100 immertion ).