What is the recommended diagnostic workup and treatment for Castleman disease?

Castleman Disease: Diagnostic Workup and Treatment

For unicentric Castleman disease (UCD), complete surgical resection is the definitive treatment and is often curative; for multicentric Castleman disease (MCD), treatment depends on subtype—rituximab for HHV-8-associated MCD and siltuximab (anti-IL-6 antibody) for idiopathic MCD (iMCD), with R-CHOP as an effective alternative when anti-IL-6 agents are unavailable.

Diagnostic Workup

Initial Classification

The first critical step is determining whether the disease is unicentric (single lymph node station) or multicentric (multiple stations with systemic symptoms) 1, 2.

Key diagnostic elements:

• Lymph node biopsy with histopathologic examination showing characteristic features (hyaline vascular, plasmacytic, or mixed type)
• HHV-8 and HIV testing to identify HHV-8-associated MCD
• Imaging (CT or PET-CT) to assess extent of lymphadenopathy
• Laboratory markers: IL-6, IL-10, C-reactive protein, complete blood count
• For MCD: evaluate for POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes)

Diagnostic Pitfalls

The morphologic findings are nonspecific and represent a histologic pattern rather than pathognomonic features 1. Correlation with clinical history, radiology, and laboratory findings is essential. HHV-8-negative cases can be misdiagnosed, and aberrant T-cell marker expression may lead to confusion with other lymphoproliferative disorders 3.

Treatment Algorithm

Unicentric Castleman Disease (UCD)

First-line approach:

• Complete surgical resection is the preferred treatment and often curative 2, 4, 5
• All 7 UCD patients treated with complete resection in one series had no recurrence 5

For unresectable UCD:

• Asymptomatic cases: observation is acceptable 2
• Symptomatic with inflammatory syndrome: siltuximab (anti-IL-6 antibody) should be considered 2
• Symptomatic from mass effect: medical therapy (rituximab, steroids), radiotherapy, or embolization to render resectable 2

Multicentric Castleman Disease (MCD)

HHV-8-Associated MCD

First-line treatment 3:

• Rituximab monotherapy is the cornerstone (Level III, A recommendation)
• Optimize or initiate antiretroviral therapy (ART) if HIV-positive
• For severe cases or cytokine storm: add etoposide to rituximab
• If concurrent Kaposi sarcoma: combine rituximab with liposomal doxorubicin or etoposide

Key monitoring: HHV-8 viral load, IL-6, IL-10, and C-reactive protein decline rapidly after rituximab 3

Relapsed/refractory disease:

• Multiple rituximab rechallenges are safe and effective
• CHOP regimen for rituximab-refractory cases 3

Important caveat: Rituximab can cause KS reactivation/progression; combine with liposomal doxorubicin if this occurs 3. NHL risk remains elevated despite treatment, particularly HHV-8-associated lymphomas 3.

Idiopathic MCD (iMCD)

First-line treatment 6, 2:

• Siltuximab (anti-IL-6 antibody) or tocilizumab (IL-6 receptor blocker)
• Corticosteroids as supportive therapy

Subtype considerations 6:

• iMCD-IPL (idiopathic plasmacytic lymphadenopathy): generally responds well to IL-6 blockade
• iMCD-TAFRO (thrombocytopenia, anasarca, fever, reticulin fibrosis, organomegaly): more aggressive; may require early escalation to cyclosporine, rituximab, or chemotherapy

When anti-IL-6 agents unavailable:

• R-CHOP is an effective first-line alternative 5
• In one series, 4 MCD patients treated with R-CHOP achieved complete remission with no recurrence over 10-45 months 5
• Oral TCD regimen (thalidomide-cyclophosphamide-dexamethasone) is valuable for refractory cases 5

Emerging therapies 6:

• mTOR inhibitors (based on mTORC1 hyperactivation data)
• JAK-2 inhibitors (case-level responses warrant further study)

Follow-Up Considerations

• Clinical, virological, and biochemical monitoring during acute episodes 3
• Radiological response assessment with CT or PET-CT after treatment completion 3
• For HHV-8-MCD: monitor every 3-6 months for relapse and NHL development 3
• Patients should seek immediate medical attention if symptoms recur 3

Critical Clinical Pearls

The distinction between UCD and MCD fundamentally changes management—surgery for UCD versus systemic therapy for MCD. Antivirals, immunomodulators, and IL-6-blocking agents have limited value in HHV-8-associated MCD compared to rituximab 3. In resource-limited settings, R-CHOP provides a practical and effective alternative to expensive anti-IL-6 biologics for iMCD 5.