Macroprolactinomas poorly responsive to dopamine-agonists are often more aggressive and are usually termed 'resistant' but this clinical concept has always been defined empirically.
Department of Internal Medicine, Cliniques de Mont-Godinne, Mont-Godinne Hospital, Université Catholique de Louvain, B-5530 Mont-sur-Meuse, Belgium. etienne.delgrange@uclouvain.be