As a result, it is often impossible to make a definitive diagnosis of NF1 in a young child with only multiple café-au-lait spots. Even if the child is affected, it could take years before another feature of the disorder appears and confirms the diagnosis. As a result, doctors often annually reexamine such children to look for the appearance of new features. If any are found, the diagnosis is clear; if not, the question remains unsettled.

People often ask, "If year after year no additional features appear, is there an age when NF1 is ruled out?" Currently, there is no diagnostic test for NF1 and therefore no clear answer to that question. This may change as we learn more about the NF1 gene.