EBV-Associated Polymorphic Posttransplant Lymphoproliferative Disorder Presenting as Gingival Ulcers - León, Jorge Esquiche; Takahama Júnior, Ademar; Vassallo, José; Soares, Fernando Augusto; Almeida, Oslei Paes de; Lopes, Márcio Ajudarte (International Journal of Surgical Pathology, 2011)