### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
Our second son was born March 18, 2009 & seems like a very healthy 2 year old boy. At birth most of our son s back, and the back of his lower neck and a small part of his upper arm was mostly a dark chocolate brown color with extra hair growth . It was a caesarean birth without complications (I am USA Caucasian male age 55, normal healthy, 5 11 , 195 lb. & mom is a healthy Indonesian 5 4 , avg. weight, age 32 - both non-smokers) . He also has some other very small hairy brown birth marks mostly on his legs and one other quarter size brown hairy mark on his head . The hair growth on all of the brown area has been minor since birth, but hair growth is thicker and more concentrated on those areas compared to normal hair growth on the head. I don t think it is Ambras syndrome because the hair growth is relatively minor and not on his face at all. The hair is not growing at an unusually abnormal rate. We have seen no other abnormalities - he s healthy and active. Our 1st son was completely normal and is a healthy 5-year old. What might this be? What dangers if any could be in the future?

### output:

Hi... Tom Wren sen., Thanks for choosing Chat Doctor., HAIRY NEVUS..... Usually brown to dark brown in pigmentation Large surface area may involve scalp, face, trunk, or extremity May develop nodules which warrant biopsy Risk of melanoma transformation is 10-15%, and can occur in childhood Treatment ranges from conservative observation with biopsy of suspicious areas to staged excision, often involving the use of skin balloon expanders or skin grafts...or LASER therapy So don't worry... Transformation to dance is very less chance..., But always observe the following..... A--B--C--D--E--- 1) A-- Asymmetry...uneven.,2)B-- Border of nevi ...irregular with poorly defined border.,3)C-- Color...different shades from Brown to Black.,4’D-- Diameter...for than 6 mm in size.(Rubber eraser size).,5)E-- Evolving....changes with growing..., So keep in mind and avoid problematic HAIRY NEVI....ok good luck