CASE REPORT DOI: 10.3904/kjim.2009.24.2.156 Acute Fibrinous and Organizing Pneumonia Following Hematopoietic Stem Cell Transplantation Sang Min Lee1, Jae-Jung Park2, Sun Hee Sung3, Yookyung Kim4, Kyoung Eun Lee2, Yeung-Chul Mun2, Soon Nam Lee2 and Chu Myong Seong2 1Department of Internal Medicine, Inje University College of Medicine, Busan, Korea Departments of 2Internal Medicine, 3Pathology and 4Radiology, Ewha Womans University School of Medicine, Seoul, Korea A 60-year-old man presented with cough, sputum, and dyspnea. He had a history of acute myeloid leukemia and hematopoietic stem cell transplantation with chronic renal failure. Chest CT scans showed miliary nodules and patchy consolidations. Histological examination revealed numerous fibrin balls within the alveoli and thickening of the alveolar septum, both of which are typical pathological features of acute fibrinous and organizing pneumonia (AFOP). We report the first case of AFOP following allogeneic hematopoietic stem cell transplantation. (Korean J Intern Med 2009;24:156-159) Keywords: Acute fibrinous; organizing pneumonia; Hematopoietic stem cell transplantation; Graft-versus-host disease INTRODUCTION CASE REPORT The incidences of hematopoietic stem cell transplan- tation (HSCT) and graft-versus-host disease (GVHD) are increasing. In particular, 40-60% of patients with HSCT sometimes develop pulmonary complications, with the incidence varying according to the type of transplant, conditioning regimen, underlying disease, and age of the patient. Pulmonary complications encompass various noninfectious conditions, including pulmonary edema, diffuse alveolar hemorrhage, idiopathic pneumonia syndrome, bronchiolitis obliterans, and cryptogenic organizing pneumonia (COP) [1]. There also exist unusual histological patterns with predominantly intra-alveolar fibrin and organizing pneumonia, which do not meet the criteria for acute interstitial pneumonia or COP. Thus far, there are only a few reports describing these findings [2- 4]. In this paper, we describe a case of intra-alveolar fibrin and organizing pneumonia following allogeneic HSCT. Received: May 4, 2007 Accepted: June 15, 2007 A 60-year-old man, who had no history of smoking, was diagnosed with acute myeloid leukemia (FAB classifi- cation M1) in February 2005. He was treated with anthracyclin and cytarabine arabinoside for remission induction and postremission therapy. During the first remission induction period, he developed chemotherapy- related pneumonia and sepsis for 21 days. At the second induction chemotherapy, we confirmed a complete remission through bone marrow biopsy and aspiration. Next, we tested his sibling’s human leukocyte antigen (HLA) in an attempt to find a stem cell donor. Completely matched HLA (A, B, C, and DR) and ABO-matched blood were detected in his 55-year-old sister. From his sister, we collected the G-CSF-mobilized stem cells from peripheral blood and harvested the bone marrow. The total concentrations of the various components of the harvested cells were as follows: total nuclear cells (TNCs), Correspondence to Yeung-Chul Mun, MD Division of Hematology & Oncology, Department of Internal Madicine, Ewha Womans University School of Medicine, 911-1 Yangchun-gu, Mok-dong, 158-710 Seoul, Korea Tel: 82-2-2650-2777, Fax: 82-2-2650-5062, E-mail: yeungchul@ewha.ac.kr