Cyclic Thrombocytopenia Misdiagnosed as Immune Thrombocytopenia (ITP): Diagnostic and Therapeutic Lessons.

Cyclic thrombocytopenia (CTP) is a rare hematological disorder characterized by periodic fluctuations in platelet counts, resulting from diverse causes, including endocrine, immune-mediated, and idiopathic mechanisms. The cyclical nature of CTP often leads to misdiagnosis as immune thrombocytopenia (ITP), resulting in inappropriate long-term treatments and associated complications. We report the case of a 60-year-old woman who experienced lifelong platelet variability, including during pregnancy and post-menopause, after being diagnosed with ITP in her early 20s. Over decades, she underwent extensive ITP-directed therapies, including corticosteroids, intravenous immunoglobulin (IVIG), rituximab, splenectomy, and thrombopoietin receptor agonists (TPO-RAs) like eltrombopag and avatrombopag. Persistent platelet cycling prompted a reevaluation of her condition, leading to a revised diagnosis of CTP. Her treatment was adjusted by increasing the avatrombopag dose, with additional consideration for cyclosporine A (CSA) and danazol if platelet cycling persisted. This case emphasizes the diagnostic challenges posed by CTP, which is often overlooked until ITP treatments fail. Regular biweekly platelet monitoring may facilitate earlier diagnosis. Better clinical awareness and clearer diagnostic guidelines are needed to reduce misdiagnosis and prevent unnecessary interventions.