1. Unit of Lymphoid Malignancies, Department of Oncohematology, San Raffaele Scientific Institute, Milan, Italy
2. Department of Internal Medicine, University of Vienna, Vienna, Austria
3. Division of Hematology, Ospedale Cervello, Palermo, Italy
4. Division of Gastroenterology, Ospedale Regina Margherita, Rome, Italy
5. Division of Hematology, Azienda Ospedaliera e Universitaria San Giovanni Battista, Turin, Italy
6. Oncologia Medica 3, Istituto Nazionale dei Tumori, Milan, Italy
7. Divisione di Ematologia, AO Santa Maria Nuova, Reggio Emilia, Italy
8. Dipartimento di Oncologia, Ematologia e Malattie dell'Apparato Respiratorio, Università di Modena e Reggio Emilia, Modena, Italy
9. Gastroenterology Unit, San Raffaele Scientific Institute, Milan, Italy
10. Institute of Pathology, University of Vienna, Vienna, Austria
11. M.P. and C.P. share senior authorship.
12. Pathology Unit, San Raffaele Scientific Institute, Milan, Italy