This case idea was taken from a talk by Dr. Yvonne Wu for the pediatrics subspecialties elective.
You see a 20 month old toddler, brought in because of stumbling. The child was able to walk fine several days ago, but now looks uncoordinated with rhythmic jerking of the limbs. When you examine the child, you notice his eyes have rapid, dancing movements. They are spontaneous, arrhythmic conjugate saccades in all directions.
Challenge: Unfortunately, this is a paraneoplastic syndrome associated with a tumor. What tumor are you worried about?