A case of paroxysmal nocturnal hemoglobinuria presenting with intra-abdominal bleeding due to splenic rupture, developing renal infarct S. UZUN*, N. ALPAY*, G. B. OZTURK*, B. SAKA*, M. YENEREL † , N. ERTEN*, M. A. KARAN*, C. TAS ¸ CIOGLU* INTRODUCTION Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal stem cell disorder, characterized by increased sensitivity of the erythrocytes to comple- ment. It is characterized with intravascular hemolysis, hemoglobinuria, and life-threatening thrombosis. Usu- ally, PNH begins insidiously with a chronic course. The *Division of General Internal Medicine, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey † Division of Hematology, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey Correspondence: Sami Uzun, Division of General Internal Medicine, Department of Internal Medicine, Istanbul Medical Faculty, Istanbul University, 34 390, Capa, Istanbul, Turkey. Tel.: +90 212 414 2000/31478; Fax: +90 212 532 4208; E-mail: drsamiuzun@gmail.com doi:10.1111/j.1751-553X.2007.00949.x Received 27 January 2006; accepted for publication 19 March 2007 Keywords Intrabdominal bleeding, paroxysmal nocturnal hemoglobinuria, renal infarct, splenic rupture, thrombocy- topenia SUMMARY Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disorder char- acterized by intravascular hemolysis, hemoglobinuria, and thrombosis. Thrombotic attacks are life threatening and are responsible for nearly 50% of PNH-related deaths. Compared with thrombotic events, bleeding related to thrombocytopenia in PNH is quite rare. This report describes an atypical clinical presentation with problems in the diagnosis and management of a woman who presented with a splenic infarct followed by massive intra-abdominal bleeding due to splenic rupture. She also developed a renal infarct during hospitalization after diagnosis. INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY Ó 2007 The Authors Journal compilation Ó 2007 Blackwell Publishing Ltd, Int. Jnl. Lab. Hem. 2007, 29, 1–6 1