Clinical Reasoning: A 15-year-old boy with bilateral wrist pain in the setting of weight loss

A 15-year-old previously healthy boy was referred for further evaluation of wrist pain. Right and left wrist pain started 2 years ago and got significantly worse in the setting of intentional 25-pound weight loss over 6 months. He also had numbness in the 4th and 5th digits of his left hand for the last 3 months. Neurologic examination was notable for weakness of both thumb abduction, finger abduction, and flexion of 4th and 5th digits on the left. There was decreased sensation to pinprick in palms, as well as trace deep tendon reflexes at biceps, triceps, and brachioradialis.