Concurrent Idiopathic Multicentric Castleman Disease with TAFRO and Sjögren's Syndrome in a Young Patient: A Challenging Diagnostic Overlap.

Background: Idiopathic multicentric Castleman disease (iMCD) with TAFRO syndrome (characterized by thrombocytopenia, anasarca, fever, reticulin fibrosis/renal failure, organomegaly) is a recently described disorder. The diagnostic criteria for iMCD-TAFRO exclude patients with concomitant autoimmune diseases such as primary Sjögren's syndrome. However, recent case reports suggest that although rare, these conditions may coexist. Case report: We report the case of a 37-year-old woman who presented with escalating systemic inflammation, cytopenias, anasarca, renal dysfunction and organomegaly, with lymph node biopsy suggestive of Castleman disease. Simultaneously, dense lacrimal gland hyperplasia with histopathology demonstrating lymphoepithelial sialadenitis and strongly positive anti-Ro52 antibodies led to a diagnosis of Sjögren's syndrome. Given the rapid clinical deterioration and marked hyperinflammation, corticosteroid therapy and tocilizumab were implemented, leading to sustained remission. Conclusion: This case illustrates the diagnostic complexity posed by overlapping features of Idiopathic multicentric Castleman disease with TAFRO syndrome and Sjögren's syndrome and reinforces the need to reconsider existing diagnostic criteria to ensure timely diagnosis and effective treatment. Epidemiologically, this is also a rare case of iMCD with TAFRO syndrome in a patient of African descent, contrasting with previous reports predominantly involving Asian individuals. LEARNING POINTS: Idiopathic multicentric Castleman disease (iMCD) with TAFRO syndrome (thrombocytopenia, anasarca, fever, reticulin fibrosis/renal failure, organomegaly) (iMCD-TAFRO) is a rare, life-threatening disorder marked by severe systemic inflammation and multiorgan failure, and early recognition and timely initiation of immunomodulatory therapy are critical for positive outcomes.Although current diagnostic criteria for iMCD-TAFRO exclude patients with concomitant autoimmune diseases such as Sjögren's syndrome, an increasing number of case reports suggest that these conditions may coexist, challenging existing definitions and suggesting a potential physiopathological overlap.This case highlights the diagnostic challenge posed by the coexistence of these conditions and underscores the need for an individualized assessment integrating clinical, laboratory, and immunological findings.