Aim To assess the prevalence of acquired diverticulum of the appendix (DA), including incipient forms and its possible significance as a marker of local/regional neoplasms.

Materials and Methods The pathology database at Hvidovre Hospital was searched for appendix specimens, received between 2001 and 2010, coded for DA or for a space-occupying lesion. Slides were reviewed to determine DA status and the nature of lesions possibly causing DA.

Result Among 4413 appendix specimens, DA were identified in 39 (0.9%, CI 0.6% to 1.2%) cases, 17 (43.6%, 28.0% to 59.2%) of which additionally harboured an appendiceal neoplasm/neoplastic precursor, whereas this figure was 1.2% (CI 0.9% to 1.6%) for non-DA specimens (p<0.0001). Six of the 39 DA specimens comprised incipient DA, three of which coexisted with appendiceal neoplasms. In addition, local/regional non-neoplastic lesions (six cases) and colorectal carcinomas (four cases) coexisted with DA.

Conclusion DA has significance as a putative marker of local/regional neoplasms. Therefore, a DA specimen proved significantly more likely to harbour a neoplastic growth than a non-DA counterpart. Submission for microscopy of the entire DA specimen, whether transmural or only incipient, and a comment in the pathology report on the occasional concurrence of local/regional neoplasms in this setting seem appropriate. The observation of DA may thus provide a valuable contribution in the diagnostic process.