A 46-year-old woman attended a general practice surgery with a
two week history of discomfort in the right side of her upper back.
She complained of the pain when driving, especially when leaning
back into the car seat and felt more comfortable when grasping the
steering wheel with her left hand only.
There was no history of recent falls, trauma or surgery and she
is otherwise fit and well with an unremarkable past medical
history. She attended the surgery after catching sight of her back
in a mirror:
She is currently unemployed and started regularly playing online
games four months ago.
What is the most likely diagnosis?