Every manuscript that passes an initial scope and similarity check is sent for double-blind peer review: reviewers are not told who the authors are, and authors are not told who reviewed.
Whether the case is worth reporting, whether the clinical account is complete and internally consistent, whether the conclusions follow from what is described, whether the literature is fairly represented, and whether consent and ethics are properly documented.
Authors may appeal a decision once, in writing, addressing the specific reviewer points. Appeals are handled by an editor who was not involved in the original decision.