ORIGINAL ARTICLE Aplastic anemia and concomitant autoimmune diseases Magnus P. Stalder & Alicia Rovó & Jörg Halter & Dominik Heim & Tobias Silzle & Jakob Passweg & Johannes Rischewski & Martin Stern & Caroline Arber & Andreas Buser & Sandrine Meyer-Monard & André Tichelli & Alois Gratwohl Received: 5 September 2008 / Accepted: 11 December 2008 / Published online: 13 January 2009 # Springer-Verlag 2009 Abstract The association of aplastic anemia (AA) with other autoimmune diseases (AID) has been described but so far not systematically evaluated. We assessed the incidence and the outcome of concomitant AID in a retrospective, single-center study of 243 patients with severe AA treated between 1974 and 2006 with either immunosuppression (186) or hematopoietic stem cell transplantation (57) and a median follow-up time of 9.3 years (0–33). Clinically manifest AID were observed in 24 out of 243 (10±3.7%) patients. Age at diagnosis of AA was significantly younger in patients without AID compared to patients with AID (median, 20 versus 52 years; P <0.001). In 12 patients where the diagnosis of AID was done before AA therapy, response to antithymocyte globulin was good for AA (ten out of 12) but not for AID (2 out of 12). In 13 patients in which AID occurred after first-line therapy, the median time to the AID was 7 years (range 3 months–27.5 years). Keywords Aplastic anemia . Autoimmune diseases . Antithymocyte globulin Introduction Aplastic anemia (AA) is defined as a pancytopenia with unexplained bone marrow hypocellularity. Acquired AA can be considered in most cases as a T cell-mediated autoimmune disorder, targeted against the hematopoietic progenitors, leading to the failure of the bone marrow [1]. Viral infections, drugs, chemical exposure, pregnancy, or unknown agents seem to trigger the autoimmune dysregu- lation in patients with predisposition. Associations of AA and other autoimmune diseases (AID) have been shown in single case reports [2, 3]. However, so far, there are no published data on a systematic review of concomitant AID in AA patients. Moreover, data on the impact of immuno- suppressive strategies to treat AA, e.g., antithymocyte globulin (ATG) and cyclosporine A (CSA) on the outcome of AID, are scarce [4]. We sought to determine the incidence and characteristics of concomitant AID diagnosed before or during the course of AA and to compare AA patients with and without AID. Materials and methods This single-center, retrospective cohort study included all 243 patients with the diagnosis of AA, treated at the University Hospital Basel, between 1974 and 2006. The severity of AA was defined according to the widely accepted criteria described by Camitta [5]. The general treatment strategy was uniform with only minor changes throughout the observation period. Patients younger than 40 years with a matched sibling donor received hemato- poietic stem cell transplantation (HSCT) as first-line therapy. Older patients and without an eligible sibling donor were treated with intensive immunosuppression Ann Hematol (2009) 88:659–665 DOI 10.1007/s00277-008-0671-9 M. P. Stalder : A. Rovó : J. Halter : D. Heim : T. Silzle : J. Passweg : J. Rischewski : M. Stern : C. Arber : A. Buser : S. Meyer-Monard : A. Tichelli : A. Gratwohl Basel Stem Cell Transplant Team, University Hospital Basel, Basel, Switzerland A. Rovó (*) Division of Hematology, University Hospital Basel, Petersgraben 4, CH-4031 Basel, Switzerland e-mail: rovoa@uhbs.ch