Diagnosis has no role. Dr. B would charge an established visit since the patient was seen within the last 3 years, same specialty.
Interpret the phrase "new patient" to mean a patient who has not received any professional services, i.e., E/M service or other face-to-face service (e.g., surgical procedure) from the physician or physician group practice (same physician specialty) within the previous 3 years.
He is an established patient. In my AMA standard CPT 2010 there is like a flowchart titled "Decision tree for new vs established patient". It is on page 2.