Recurrent and Progressive Abdominal Pain and Enteritis in a Japanese Patient with Paroxysmal Nocturnal Hemoglobinuria

This case report describes a young male patient with recurrent abdominal pain persisting for more than 16 months. Clinical investigations showed signs of inflammation and pancytopenia. A diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) was made 9 months after the onset of the abdominal pain, following endoscopic examinations that revealed evidence of a previously unknown hemorrhage. Regular monitoring indicated that the abdominal pain was associated with elevations in lactate dehydrogenase, C-reactive proteins, and D-dimer levels. The patient started treatment with the complement inhibitor eculizumab shortly after it was approved for use in Japanese PNH patients with hemolysis. Resolution of the abdominal pain and normalization of clinical parameters were noted within 3 weeks from treatment initiation. 1. Introduction Paroxysmal nocturnal hemoglobinuria (PNH) is a rare and progressive hematopoietic stem cell disorder in which hematopoietic cells are deficient in glycosylphosphatidylinositol (GPI), which leads to a lack of the complement inhibitor proteins CD55 and CD59 on the surface of blood cells. This results in the characteristic intravascular hemolysis of red blood cells, along with platelet activation and aggregation [1]. PNH is fatal in up to 35% of patients within 5 years of diagnosis and in up to 50% of patients within 10 to 15 years of diagnosis [2, 3], largely as the result of thrombosis. Patients with PNH have an approximately 62-fold greater risk of thrombosis compared with the general population [4] and an estimated 10.2-fold increase in mortality risk [3]. The liver, kidney, brain, and gut are common sites of thromboembolism, and up to 44% of patients with PNH will experience a clinically evident thrombosis [3, 5]. Although the etiology and symptoms of PNH are similar in Japanese/Asian and Western patients, it has been suggested that the clinical course of the disease may differ between the ethnic groups [6]. Here, we describe a Japanese patient who experienced extensive abdominal pain over a period of 16 months accompanied by pancytopenia, signs of inflammation, and thickening of the intestinal wall. 2. Case Study In May 2009, a 22-year-old male with no relevant personal or family medical history started experiencing lower abdominal pain lasting for several days with repeated periods of exacerbation and remission. In December 2009, the patient attended an outpatient department for detailed examination, as the abdominal pain had not resolved. Routine tests revealed pancytopenia, with a white blood cell (WBC) count of 2,400/μL (lower