Q: Would a follow-up case report be regarded as duplicate submission or salami slicing?
If I submitted a follow up case report for the same case which was already reported once before, would it be considered as a duplicate submission or a salami slicing?
Publishing a follow-up on a previously published case report will depend on the novelty and importance of the follow-up. As long as you clearly reference the previous publication, mention that this is a follow-up study, and do not include the same figures/tables from the previous publication, it will not be considered unethical.
However, to be on the safe side, it is best to inform the journal editor regarding the previous publication at the time of submission. You can mention this and provide a link to the published case report in the cover letter to avoid any ethical concerns later.