Pure Red Cell Aplasia Associated With Thymic Tumors, a Nationwide Retrospective Study.

Pure red cell aplasia (PRCA) is the most frequent autoimmune cytopenia associated with thymic tumors (TTs). In a nationwide retrospective study, we included 41 patients (22 women, median age 62 years). At PRCA diagnosis, the mean hemoglobin level was 6.6 ± 2.1 g/dL, and the reticulocyte count was 6 ± 5 × 109/L. PRCA was diagnosed before TT (8%, median delay 52 months), simultaneously (46%) or after TT (46%, median delay 34 months). Fourteen patients (34%) had definite Good syndrome. Thymectomy without immunosuppressive treatment provided a single sustainable PRCA response. Twenty-two patients (54%) experienced multiple PRCA relapses (Median 2). When PRCA was present at TT diagnosis, the risk of PRCA relapse was higher (p < 0.01), while TT staging, TT relapse, and Good syndrome were not associated with PRCA relapses. Corticosteroids led to a 77% initial response rate with frequent relapses during taper or at discontinuation. Cyclosporine A provided a 71% response rate. Overall response rates and time to response were similar with corticosteroids and cyclosporine A. Sirolimus led to a 50% response rate in refractory cases. Severe infectious events requiring hospitalizations were frequent (44%). After a mean follow-up of 50 months, five patients (12%) died, three of whom died from TT relapse. Good syndrome was not significantly associated with an increased risk of infection, PRCA relapse, or death. Our findings highlight the severe phenotype of the association of TT and PRCA. While most patients achieve PRCA response under immunosuppressive therapy, high infection incidence and thymoma relapse are responsible for severe morbidity.