Bipolar diagnosis or autism

Is it possible to misdiagnois autism as bipolar disorder?  My son was diagnosed at 14 with bipolar, after an episode of depression.  He had manic episodes of constant talking, irrational thinking, and anger outbursts.  He was medicated with lithium, risperadol and paxil.  He stayed ont that for several years.  Now at 20, he refuses to take medication.   So far he has not fallen into depression, and does not appear manic -  but he still has occasional anger outbursts.   As a child, he played alone a lot, and was content to play with legos for hours.   He also did not like loud noises and as a toddler used to cover his ears when he thought the TV was too loud.   I'm wondering if he was properly diagnosed.   He did fairly well in school, except when he became disinterested during the depression.    Is it possible to confuse the two conditions?

[mjthewriterdad]

or both?   There can be differeny issues going on.