Castleman's disease and related disorders

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Castleman disease (CD) is an eponym for three distinct clinicopathologic disorders.
• Localized CD presents as either hyaline-vascular (HV) type (asymptomatic mass, abnormal lymphoid tissue) or plasma cell (PC) type (systemic inflammation, B cell hyperreactivity).
• Multicentric CD is a systemic B cell lymphoproliferation with mixed histology, peripheral lymphadenopathy, and multisystem involvement.

Purpose of the Study:

• To discuss the three disorders classified under the Castleman disease eponym.
• To differentiate the clinical and histological features of localized HV, localized PC, and multicentric CD.
• To contextualize localized PC and multicentric CD within the spectrum of idiopathic plasma cell disorders.

Main Methods:

• Review and discussion of existing literature and clinicopathologic data on Castleman disease variants.
• Comparative analysis of histological findings, clinical presentations, and disease behavior.
• Classification of CD subtypes within a framework of B cell lymphoproliferative disorders and lymphocyte traffic.

Main Results:

• Localized HV CD is characterized by hypervascularity and abnormal lymphoid tissue, often presenting as a localized mass.
• Localized PC CD involves plasma cell infiltration and systemic inflammation, appearing as a localized chronic reaction.
• Multicentric CD is a systemic disorder with mixed histology, systemic symptoms, and potential for clonal B cell outgrowth, related to POEMS syndrome.

Conclusions:

• Castleman disease encompasses a spectrum of B cell disorders ranging from hyperplasia to dysplasia.
• Localized PC CD is viewed as a hyperplastic disorder, while multicentric CD is considered dysplastic.
• These conditions are linked to idiopathic plasma cell disorders and involve peripheral-node-bound B cells.