Crick In The Neck

Question:  An 8 week old otherwise healthy baby is referred to you for a neck mass.  On evaluation you note flexion of the neck toward the affected side.  His mother reports no medical problems other than a "hip problem" at birth.  What is the diagnosis?  [Answer will be posted with next week's new question]

Answer to last week's question, "More Than Meets The Eye" (May 16, 2016): 

Heerfordt syndrome.