Collagenous colitis presenting with bloody diarrhea and rectal erosions in a patient with celiac disease: a case report oleh Antonio Carroccio, Tiziana Catalano, Marilena Fiorino, Accursia Bongiovì, Giuseppe Napoli, Lidia Di Prima, Giuseppe Ambrosiano, Michele Pace, Antonino Scaturro, Gaetana Di Fede