Why is this unlikely to be a typical perforated acute appendicitis?
The presence of an endoluminal mass at the tip of the appendix with ulceration, coupled with the relatively little fat stranding surrounding the appendix itself make acute bacterial appendicitis unlikely. A tumour of the appendiceal tip is highly likely and the surgeon should be notified before the patient is taken to the operating room.
Retroperitoneal abscess seen to arise from the tip of the appendix. This was initially read as complicated appendicitis. However, notice how there is an expansive tissue-density rounded lesion in the appendiceal tip. This should raise suspicion of an underlying tumour. Also, note how little fat stranding there is surrounding the tip of the appendix. This is also quite unusual if considering typical acute appendicitis.