Hi Cecile thanks for posting! We do offer the option to export your diagram as an editable Visio file but unfortunately it is not possible to edit a diagram exported in PDF JPEG or PNG format. Please see our Export/Download your Lucidchart Documents article for more information about these options. 

The current functionality of our Microsoft integrations allows you to quickly select and insert your Lucidchart diagrams into Powerpoint Word and Excel but to edit these diagrams you must open them in the Lucidchart editor. However we're always looking for ways to improve Lucidchart and we welcome your feedback on this. If you would like the ability to edit inserted Lucidhcart diagrams within Office applications please feel free to submit your thoughts to our Product Feedback space. Feedback submitted here is reviewed by our Product team so this is the best way to advocate for a new feature you would like to see.