An addendum is additional information added on to your pathology report after it was finalized by your pathologist. Most addendums are added on to the bottom of the original report.
An addendum is usually created to tell you and your other doctors the results of additional tests that were performed such as immunohistochemistry, fluorescence in situ hybridization (FISH), next generation sequencing (NGS), or other molecular tests. The results of an internal or external consultation or review of your case may also be included in an addendum.
The purpose of an addendum is to communicate additional information which supports the original diagnosis or interpretation. Information that leads to a change in diagnosis should be reported as an amendment, not an addendum.