A primary care provider notes painless, hard lesions on a patient's external ears that expel a white crystalline substance when pressed. what diagnostic test is indicated?

The right answer is Tophus.

A tophus (tophi in plural) is a subcutaneous deposit of uric acid crystals surrounded by inflammatory cells. They are most commonly found in ligaments and soft tissues around the joints, as well as on the ears or Achilles tendon. The tophus is a classic manifestation of the most advanced forms of gout.