My baby was diagnosed with mastocytoma

[dpops]

Hi all, my 1-year old daughter has just been diagnosed with mastocytoma. She has one little bump (she has had it from birth) and it blisters every couple of months, otherwise no symptoms. After 3 GPs and a junior dermatologist failed to diagnose it, we saw a consultant dermatologist (who is apparently a well-known professor of dermatology) who looked at it and immediately recognised it as mastocytoma. He did a visual examination and tested for Darier's sign but that was it. He said it is benign, told us to go away and do some reading on the condition and prescribed steroid cream. He seemed pretty relaxed about it and opined it would most likely go away as my daughter grows older. However, having now read extensively about this condition, I am concerned that he has not done any actual tests (like a biopsy), that he cannot know whether it is in fact benign just by looking at it and that he has not advised on any allergy risks or indeed any risks. Does anyone have any experience with mastocytoma in young children? Do we need to do further tests and, if so, what tests?