Do case reports require ethical approvals? Do case reports involving people with medical ailments require ethical approvals? If they do not, then why?

I am located in Sweden, but am (almost) equally interested in conditions elsewhere.
From a legal point of view, in the United States, preparation of a case report for publication does not require review by the ethics board because case reports do not meet the legal definition of "research" (according to most interpretations):


  Case reports submitted for publication do not strictly meet the criteria of research. Although a case report (defined as a retrospective analysis of one (1), two (2), or three (3) clinical cases) may be illustrative, it does not meet the Federal Policy for the Protection of Human Subjects definition of Research, which requires an investigation that contributes to generalizable knowledge about a disease or condition. Instead, a case report is intended to develop information to be shared for medical or educational purposes.


(Source: Tufts)

Many institutions therefore do not require any kind of review for publishing case reports. For example:


  Q:  Do faculty who prepare a  case report as an article for submission to a journal require IRB approval prior to preparation?
  
  No.  A case report is a medical/educational activity that does not meet the DHHS definition of “research”, which is: "a systematic investigation, including research development, testing and evaluation, designed to develop or contribute to generalizable knowledge."  Therefore, the activity does not have to be reviewed by a JHM IRB.


(Source: John Hopkins Medicine)

(Another example: University of Wisconsin - Madison)

(Another example: Columbia)

As pointed out by Fomite, some institutions have an IRB make the determination that a study is "not human subjects research" even for a case study. For example:


  A number of studies submitted to the UNC-Chapel Hill IRB are deemed “not human subjects” research which means, once reviewed and so designated, no further involvement with the IRB is needed unless a change in the study might alter that decision. This designation can be given to studies that involve human beings but are not considered to be research in the federal regulations (e.g., not systematic, as in single subject case studies and/or are not designed to contribute to generalizeable knowledge, as in program evaluation or quality improvement projects) or when information is collected from humans but is not about them (e.g, a survey of public health department directors about the content of programs offered).  When a student has a study that might qualify for a “not human subjects research” designation from the IRB, the online IRB application will be shortened considerably.  Once submitted, the IRB will review the application and let the student know if it agrees with the “not human subjects research” determination. If it does not agree, then a longer IRB application will be necessary.


(Source: UNC Nursing)