Case Reports differ than other types of primary research articles, there being no research methods and results to report. Instead you are reporting an N of 1, everything important about the case. They are usually brief, just one or a few pages and contain the following:
* A note about writing your title, keywords and abstract - be specific enough that a reader could infer the content based on these sections only. Many databases and indexes only search the titles, keywords, and abstract of articles, NOT the full text.
The above list is an example. Many journals, while having their own instructions for authors and specifications, will defer to the reporting guidelines for Case Reports, called CARE. You can find the CARE checklist on the CARE website (https://www.care-statement.org/checklist). A list of all study type reporting guidelines can be found on Equator Network's website (https://www.equator-network.org/).