An addendum is additional information added on to your report after it was finalized and sent by your pathologist to your other doctors. An addendum is usually created to tell you and your other doctors the results of additional tests that were performed such as immunohistochemistry or molecular analysis.
The results of an internal or external consultation or review of your case may also be included in an addendum.
An addendum is only meant to convey additional information which support the original diagnosis or interpretation. Information that leads to a change in diagnosis should be reported as an amendment, not an addendum.