Can Castleman disease be diagnosed on bone marrow biopsy?

Diagnosis of Castleman Disease on Bone Marrow Biopsy

Castleman disease is not typically diagnosed through bone marrow biopsy alone, as the primary diagnostic tissue is lymph node biopsy. While bone marrow may show secondary changes in some cases, it is not the standard diagnostic specimen for Castleman disease.

Diagnostic Approach for Castleman Disease

• The diagnosis of Castleman disease requires excisional lymph node biopsy, which allows for proper histopathological evaluation of the characteristic features 1, 2
• Core biopsies should only be considered when lymph nodes are not easily accessible (such as retroperitoneal masses), and fine-needle aspirations are inappropriate for reliable diagnosis 3
• Histopathological examination of lymph nodes reveals characteristic features including:
  • Hyaline-vascular variant: Regressed germinal centers with penetrating hyalinized vessels and concentric layering of lymphocytes ("onion-skinning") 2
  • Plasma cell variant: Hyperplastic germinal centers with sheets of plasma cells in the interfollicular region 2, 4

Role of Bone Marrow in Castleman Disease

• Bone marrow examination is not routinely recommended or required for the primary diagnosis of Castleman disease 1, 2
• Bone marrow may show nonspecific findings in multicentric Castleman disease (MCD), including:
  • Lymphoplasmacytic infiltrates that are generally sparse 3
  • Possible reticulin fibrosis in the TAFRO subtype (Thrombocytopenia, Anasarca, Fever, Renal dysfunction/Reticulin fibrosis, Organomegaly) 1
• Bone marrow biopsy may be performed in Castleman disease patients to evaluate for:
  • Unexplained cytopenias 3, 5
  • Possible concomitant myeloid neoplasms, which have been reported in some patients with Erdheim-Chester disease but are not typical of Castleman disease 3

Diagnostic Recommendations

• The primary diagnostic approach for Castleman disease should include:
  • Excisional lymph node biopsy whenever possible 1, 2
  • Immunohistochemical studies on the lymph node tissue 2
  • Correlation of histopathologic findings with clinical and laboratory parameters 1
• Clinical and laboratory findings that support the diagnosis include:
  • Unicentric: Single enlarged lymph node region, often asymptomatic 1, 6
  • Multicentric: Multiple enlarged lymph node regions with systemic symptoms, anemia, elevated inflammatory markers, and hypergammaglobulinemia 1, 7
• Testing for HHV-8 and HIV status is essential for proper classification of multicentric Castleman disease 1, 7

Clinical Pitfalls and Considerations

• Castleman disease is often misdiagnosed or diagnosed with delay due to its rarity and nonspecific presentation 4
• Castleman-like histological changes can be seen in reactive lymph nodes in patients with autoimmune diseases, lymphomas, and infections, making clinicopathologic correlation crucial 1
• PET/CT imaging is valuable for staging and treatment response evaluation in Castleman disease 4
• Bone marrow findings alone are insufficient for diagnosis and must be interpreted in the context of lymph node histology and clinical presentation 1, 2

In summary, while bone marrow examination may reveal abnormalities in patients with Castleman disease, particularly in multicentric variants, it is not the primary diagnostic tool. The definitive diagnosis relies on characteristic histopathological findings in lymph node tissue combined with appropriate clinical and laboratory features.