Can a 20 month old child have Alopecia?
This is unlikely. Most children without much hair are just delayed growing their hair. Assuming the the hair is patchy, one would look to your pediatrician for the diagnosis of ringworm, alopecia areata (rare). Complete absence of hair on the head and eyebrows could reflect other types of alopecias, but I do not want to write a book on the subject without knowing more about what your concerns are.