lichen striatus or linear epidermal nevus

hy my son is 18 month old and when he was 11 months on his left arm appeared a lesion starting from his shoulder and finishing next to his finger, it looks like an eruption with small papules, i  went to his pediatric  and he told it could be sclerosis tuberous i was very worry and i want to see a dermatologist and he told me is lichen striatus anf i wanted aq second opinion from a dermatologist and this second one told me is lenear epidermal nevus i don't know how to believe i now that sclerosis and LEN are dangerous and i am very concerned for my boy future i dont know what to do to be sure what is exactly what is your advice, i