. ▁This , ▁in ▁turn , ▁imp edes ▁vision , ▁feed ing , ▁and ▁movement . ▁Ar ound ▁ 2 5 – 3 0 % ▁of ▁t urt les ▁with ▁external ▁tum ours ▁also ▁have ▁internal ▁tum ours , ▁primarily ▁in ▁heart , ▁l ungs ▁and ▁kid ne ys . ▁ ▁F P ▁inc idence ▁is ▁highest ▁among ▁imm ature ▁and ▁ju ven ile ▁green ▁t urt les , ▁while ▁it ▁is ▁rare ▁in ▁adult s . ▁The ▁suggestions ▁for ▁this ▁pattern ▁include ▁the ▁tum ours ▁can ▁re gress ▁and ▁be ▁c ured , ▁which ▁has ▁been ▁documented ▁in ▁some ▁individuals , ▁even ▁when ▁tum ours ▁were ▁severe . ▁However , ▁the ▁responses ▁that ▁cause ▁these ▁tum our ▁re gress ions ▁is ▁unknown . ▁Second ly , ▁the ▁ju ven ile ▁individuals ▁with ▁F P ▁might ▁die ▁before ▁reaching ▁ad ul th ood . ▁ ▁Pro gn osis ▁ ▁The ▁tum ours ▁appear ▁to ▁be ▁ben ign ▁and ▁can ▁be ▁present ▁for ▁many ▁years , ▁but ▁if ▁large , ▁can ▁mechan ically ▁ham per ▁sight , ▁sw allow ing , ▁and ▁sw imming , ▁which ▁may ▁ultimately ▁be ▁fatal . ▁While ▁external ▁tum ours ▁ham per ▁movement ▁and ▁sight , ▁internal ▁tum ours ▁inter f ere ▁with ▁system ▁function ing , ▁another ▁potentially ▁fatal ▁factor . ▁As ▁the ▁tum ours ▁progress , ▁individuals ▁with ▁large ▁numbers ▁of ▁tum ours ▁may ▁become ▁an a em ic , ▁have ▁a ▁lack ▁of ▁prote ins ▁and ▁iron , ▁and ▁in ▁more ▁advanced ▁stages ▁even ▁suffer ▁from