Introduction Langerhans' cell histiocytosis (LCH) commonly presents in infants as multisystem disease, including hepato- splenomegaly, miliary and cystic lung disease with ade- nopathy and anterior mediastinal thymic enlargement. Bone disease in this age group may be absent. In the last decade, there have been reported of four untreated cases of LCH in infants with thymic calcifications [1±3]. The most obvious example was seen on plain films, but defin- itive findings of calcifications were seen only on CT. We report four new cases. All had CT evidence of thymic punctate calcifications in addition to varying de- grees of lung disease. In one case, the calcifications dis- appeared on follow-up studies. Case reports Case 1 A 5-week-old boy had surgery shortly after birth for duodenal ob- struction from Ladd's bands complicating malrotation. He then had severe failure to thrive, and a diffuse rash developed; skin bi- opsy showed Birbeck granules and other characteristic findings of LCH. Plain chest films showed diffuse intersitial lung disease and a large thymus. There were no bone lesions. CT revealed the lung disease to be reticulonodular in pattern, and the thymus had many punctate calcifications (Fig.1). Despite chemotherapy, the patient deteriorated and died. There was no autopsy. Gordon D. Heller Jack O. Haller Walter E. Berdon Shashikant Sane Paul K. Kleinman Punctate thymic calcification in infants with untreated Langerhans' cell histiocytosis: Report of four new cases Received: 1 February 1999 Accepted: 10 May 1999 G.D. Heller ´ J. O. Haller Department of Radiology, SUNY Health Science Center at Brooklyn, Box 1208, Brooklyn, NY 11203, USA W.E. Berdon ( ) ) Department of Radiology, Babies & Children's Hospital of New York, 3959 Broadway, BHN 3±318, New York, NY 10032, USA S. Sane Department of Radiology; Children's Medical Center, 2525 Chicago Avenue S, Minneapolis, MN 55404, USA P.K. Kleinman Department of Radiology, University of Massachusetts Medical Center, 55 Lake Avenue N, Worcester, MA 01655, USA Abstract Four new cases of punc- tate thymic calcification in infants with untreated Langerhans' cell his- tiocytosis (LCH) are added to the four previously reported cases. All cases were shown on CT scans; plain films were rarely diagnostic. Patho- logic correlation remains elusive since the usual biopsies of the LCH have been on skin or bone biopsies. A single prior pathologic study of the thymus in untreated LCH showed microscopic calcospherites. The thymic punctate calcific densi- ties in patients with LCH may rep- resent further accretion so that the calcospherites become macroscopic. The finding of such punctate calcific densities in an enlarged thymus of an infant with skin or bone or lung disease is strongly suggestive of LCH. Pediatr Radiol (1999) 29: 813±815 Ó Springer-Verlag 1999