Castleman disease (CD) is a rare and highly heterogeneous lymphoproliferative disorder, with clinical and pathological features ranging from asymptomatic localized lesions to life-threatening systemic inflammatory responses. In recent years, the classification system of CD has been increasingly refined, with both unicentric CD (UCD) and multicentric CD (MCD) expanding into multiple subtypes with distinct clinical characteristics. Although the classification framework has become more sophisticated, some subtypes still lack specific biomarkers, and the categorization of certain entities remains controversial. This review summarizes advances in CD classification approaches over the past years, explores the clinical features and identification of newly proposed subtypes, and analyzes current challenges, aiming to provide a reference for optimizing diagnostic and therapeutic strategies.