Evidence of an inflammatory pathologic condition in "normal" appendices following emergency appendectomy

Background - Appendices removed from patients with suspected appendicitis o ften appear normal on histologic examination. Objective - To study appendix specimens for the expression of inflammatory markers as an indicator of pr esence of an inflammatory response in this subgroup of patients. Methods - Cyclooxygenase 1 and 2, prostaglandin E-2, inducible nitric oxide synthase, and major histocompatibility complex class II were investigated by immunofluorohistochemistry using confocal laser microscopy in 15 acutely inflamed appendix specimens, 39 histologically classified "normal" appendi ces, and 11 negative control specimens. Results - Strong expressions of all the inflammatory mediators were found i n the mucosa of inflamed appendices, in approximately 50% of histologically normal appendices from patients with a clinical diagnosis of appendicitis, and in none of the normal control specimens. Conclusion - This study confirms the existence of a subgroup of appendiciti s within the so-called histologically normal appendices in which evidence o f an inflammatory pathologic condition is only obvious at a molecular level . The initiating signal for this and all other forms of clinical appendicit is still remains elusive.