Case report http://dx.doi.org/10.3345/kjp.2012.55.5.177 Korean J Pediatr 2012;55(5):177-180 eISSN 1738-1061 • pISSN 2092-7258 Successful pleurodesis with OK-432 in preterm infants with persistent pleural effusion Jeong Eun Kim, MD1, Chul Lee, MD1, Kook 1 1 In Park, MD , Min Soo Park, MD , Ran Namgung, MD1, In Kyu Park, MD2 Departments of 1Pediatrics and 2Thoracic and Cardio­ vascular Surgery, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea Received: 6 September 2011, Revised: 28 October 2011 Accepted: 28 November 2011 Corresponding author: Ran Namgung, MD Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, 50 Yonsei-ro, Seo- daemun-gu, Seoul 120-752, Korea Tel: +82-2-2228-2050, Fax: +82-2-393-9118 E-mail: ranng@yuhs.ac OK-432 (picibanil) is an inactivated preparation of Streptococcus pyogenes that causes pleurodesis by inducing a strong inflammatory response. Intrapleural instillation of OK-432 has recently been used to successfully treat neonatal and fetal chylothorax. Here we report a trial of intrapleural instillation of OK-432 in two preterm infants who were born with hydrops fetalis and massive bilateral pleural effusion. Both cases showed persistent pleural effusion, refractory to conservative treatment, up to postnatal days 26 and 46, respectively. An average of 80 to 140 mL of pleural fluid was drained daily. In case 1, the infant was treated with OK-432 during the fetal period at gestation 28 weeks and 4 days of gestation, but showed recurrence of pleural effusion and progressed into hydrops. Within two to three days after OK-432 injection, the amount of pleural fluid drainage was dramatically decreased and there was no reaccumulation. We did not observe any side effects related to OK-432 injection. We suggest that OK-432 should be considered as a therapeutic option in infants who have persistent pleural effusion for more than four weeks, with the expectation of the early removal of the chest tube and a good outcome. Copyright © 2012 by The Korean Pediatric Society This is an open­access article distributed under the terms of the Creative Commons Attribution Non­Commercial License (http://creativecommons.org/licenses/by­ nc/3.0/) which permits unrestricted non­commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Key words: OK-432, Chylothorax, Infant, Premature Introduction Congenital chylothorax, although rare, is the most common form of pleural effusion in neonates. Its etiology is not fully understood, but may be related to maldevelopment of the lymphatic system. Overall mortality rates for chylothorax range from 18 to 44%, depending on associated conditions, gestational age and the duration and severity1­3). With conservative treatment, complete resolution of pleural fluid can be observed within 30 days for 80% of congenital chylothorax patients. Poorer prognosis is associated with hydrops fetalis, large pleural effusions leading to pulmonary hypoplasia, and preterm birth (<34 weeks). However, the point at which conservative treatment is considered to have failed has not been well established4). Recent reports have suggested pleurodesis with OK­432 (picibanil, Chugai Pharmaceutical Co., Tokyo, Japan), inactivated preparation ofStreptococcus pyogenes , as an alternative therapeutic option. It has been used to treat malignant pleural effusion in adults, and both chylothorax after chest surgery and cystic lymphatic malformations in the pediatric population5­7). In fetal chylothorax, OK­432 has recently been reported to have a favorable outcome8­11). For its use 177