Unicentric Castleman Disease as a Sufficient and Reversible Cause of Steroid‐Refractory Autoimmune Hemolytic Anemia in a Child

To the Editor: Autoimmune hemolytic anemia (AIHA) in childhood is an uncommon but clinically significant condition, often prompting extensive evaluation for secondary etiologies when refractory to first-line immunosuppressive therapy [1]. Among secondary causes, lymphoproliferative disorders, particularly Castleman disease, represent a well-established yet frequently underrecognized trigger of immüne-mediated cytopenias [2]. We report a 10-year-old female who presented with severe, steroid-refractory AIHA and was subsequently found to have a solitary intra-abdominal lymph node mass located in the perihepatic region, which was completely excised. Histopathological examination demonstrated unicentric Castleman disease (UCD), hyaline vascular type, supported by classical architectural features and immunohistochemical findings (CD21+/CD23+ follicular dendritic cell expansion, reactive B- and T-cell populations, absence of CD30 and HHV-8 expression). Following surgical excision, hemolysis resolved completely and persistently without the need for further immunosuppressive therapy, strongly indicating a causal relationship between UCD and AIHA in this patient [3]. The temporal and biological coherence observed in this case, namely, refractory AIHA preceding diagnosis, complete remission after tumor excision, and sustained hematologic recovery, fulfills established criteria for causality in secondary autoimmune cytopenias [4]. Surgical resection alone is widely accepted as curative in UCD, and resolution of immune dysregulation following excision has been repeatedly documented, supporting the concept that localized cytokine-driven immune activation is sufficient to induce systemic autoimmunity [5]. In conclusion, this case highlights unicentric Castleman disease as a sufficient, reversible cause of severe steroid-refractory AIHA in a pediatric patient, emphasizes the curative role of surgical excision, and underscores the importance of cautious interpretation of incidental genomic findings. We believe this report contributes to the limited pediatric literature on UCD-associated autoimmune cytopenias and reinforces the primacy of clinicopathologic correlation over speculative mechanistic expansion. The authors certify that they have participated sufficiently in gathering the intellectual content and the analysis of data. All the authors took part in the follow-up and care of the patient. Each author has reviewed the final version of the manuscript and approved it for publication. The patient's family signed the free and informed consent form. In addition, appropriate permissions have been obtained for reproduced images. The authors declare no conflicts of interest. All data generated or analyzed during this study are included in this published article (and its Supporting İnformation files).