Response to: Caution the masqueraders of Good’s syndrome on the thymoma with systemic lupus erythematosus

Abstract

We appreciate Liu et al. for their correspondence [CLRH-D20-02326] and careful review of our case-based review on postthymectomy systemic lupus erythematosus [1]. The point raised by Liu et al. regarding the possibility of Good syndrome in the reported case, considering the coexistence of thymoma and pure red cell aplasia, is well received and was considered as a differential in our case as well. Good syndrome is characterized by thymoma, hypogammaglobulinemia, and peripheral B cell lymphopenia [2]. Thymoma may precede or present simultaneously with hypogammaglobulinemia and lymphopenia; however, cases of Good syndrome diagnosed years after thymectomy have been reported in literature as well [3, 4]. In contrast to the predisposition to common infections in cases of Good syndrome [5], the patient in our report did not experience such opportunistic infections—sinopulmonary infections with encapsulated organisms, cytomegalovirus colitis, and mucocutaneous candida infections before, during, or after diagnosis of thymoma, and his infections were mostly multi-drugresistant bacterial infections in the setting of neutropenia [1]. Unfortunately, no dedicated peripheral B cell or immunoglobulin studies are available at or around the time of thymoma diagnosis. Nevertheless, as part of further work-up for his severe anemia after thymectomy, a bone marrow biopsy and flow cytometry were performed, demonstrating a normal CD4:CD8 ratio and an absence of immunophenotypic evidence of monotypic population of B cells, abnormal T cells, or increased blasts. Furthermore, later in the course of disease, at the time that patient developed autoimmunity and was diagnosed with systemic lupus erythematosus, serum protein electrophoresis (SPEP) revealed no evidence of monoclonal protein in the gamma region and diffuse patterns of gamma, alpha, mu, kappa, and lambda chains of immunoglobulins and a normal kappa:lambda ratio. While Good syndrome was certainly on the differential in our case, the lack of peripheral B cell depletion and hypogammaglobulinemia as evidence by bonemarrow flow cytometry and SPEP, respectively, makes this diagnosis extremely unlikely.