Actinomycosis of the appendix mimicking appendiceal tumor: A case report

Figure 1 Contrast-enhanced CT revealed a well-defined solid mass with strong enhancement in the base of the appendix (arrow). Peri-appendiceal infiltration was not seen.

Figure 2 US showed a heterogeneous, hyperechoic, intraluminal mass at the base of the appendix, without peri-appendiceal infiltration. We also noted focal defects at the echogenic inner mucosal layer (arrows).

Figure 3 Microscopy of appendiceal actinomycosis. An abscess composed of chronic and acute inflammatory cells was observed in a mass-like lesion (arrow), from the mucosal surface to the superficial submucosa (arrowhead) (HE, × 10).

Figure 4 Higher magnification showed a typical sulfur granule surrounded by neutrophils in the clefted abscess center (HE, × 200).