A 23 year old woman has been having pain at the base of her thumb, the pain is reproduced when lifting her 3 month old baby or changing diapers and also with forceful abduction of the thumb against resistance. What is the likely cause?

The key is C. De Quervain’s tenosiovitis. [Can be diagnosed by Finkelstein’s test: The physician grasps the thumb and the hand is ulnar deviated sharply. If sharp pain occurs along the distal radius (top of forearm, about an inch below the wrist), de Quervain's syndrome is likely].