Successful treatment of idiopathic multicentric Castleman disease with TAFRO and kidney involvement: case report and literature review.

Idiopathic multicentric Castleman disease (iMCD) is a rare hematological disease of heterogenous presentation, with symptoms ranging from mild to severe and life-threatening. A severe subtype of iMCD is characterized by thrombocytopenia, anasarca (including pleural effusion and ascites), fever, reticulin myelofibrosis or renal dysfunction, and organomegaly (iMCD-TAFRO). Early identification and treatment of iMCD-TAFRO is crucial because of its rapid onset, severe renal dysfunction and high mortality risk. However, diagnosing iMCD-TAFRO can be difficult due to a lack of diagnostic biomarkers and symptoms that overlap with a variety of lymphoproliferative, infectious, and rheumatological diseases. Although the exact etiology of iMCD-TAFRO is unknown, interleukin (IL)-6 has been identified as a critical pathological driver, and the IL-6 antagonist siltuximab is recommended as first-line treatment. While many patients with iMCD-TAFRO have abnormal kidney function and will require nephrology care, evidence describing kidney histopathology and kidney involvement in this condition is limited. Herein, we review the disease state and recent advances with a focus on renal histopathology and the mechanisms of kidney injury in iMCD-TAFRO. We also present and discuss a case report of a patient with iMCD-TAFRO and acute kidney failure. Our aim is to draw attention to the spectrum of kidney involvement in iMCD-TAFRO, as well as raise awareness to the importance of early recognition and appropriate treatment of this rare condition.