I commonly meet colleagues, resident dermatologists, and medical students who have a misunderstanding about an important point of evidence-based medicine (EBM). Their problem is rooted in their misinterpretation of the "highest level of evidence" and "current best evidence". They usually do not differentiate the crucial difference between the two. Indeed, if they cannot find the "highest level of evidence" for a certain disease, they interpret it as "not having the current best evidence".
It is important to remember that when the "highest level of evidence" cannot be found, the next level of evidence will be considered as the "best current evidence". For example, if there is no systematic review of homogenous, high quality randomized controlled trials for the treatment of a certain disease, the next level, i.e. high quality randomized controlled trial(s), will be "the current best level of evidence". So, there is a need for looking for lower levels of evidence when we could not find the higher ones. Rare diseases are common in dermatology, in many cases the "current best evidence" may be limited to a case report or a colleague's experience.