Bone marrow manifestations in multicentric Castleman disease

Area of Science:

• Hematopathology
• Oncology
• Virology

Background:

• Multicentric Castleman disease (MCD) is a rare lymphoproliferative disorder.
• Human herpes virus 8 (HHV8) is a key driver in a subset of MCD cases.
• Bone marrow involvement in HHV8-MCD requires detailed characterization for accurate diagnosis and management.

Purpose of the Study:

• To define the morphological and immunophenotypic features of bone marrow involvement in HHV8-MCD.
• To identify diagnostic markers for bone marrow infiltration in HHV8-MCD.
• To correlate bone marrow findings with clinical parameters.

Main Methods:

• Retrospective analysis of 28 bone marrow trephine biopsy (BMTB) specimens from HHV8-MCD patients.
• Immunohistochemical evaluation for markers including CD3, CD20, CD138, CD68R, HHV8-latency-associated nuclear antigen (LANA1), and Epstein-Barr virus.
• Morphological assessment of cellularity, lymphoid aggregates, and reticulin fibrosis.

Main Results:

• Bone marrow involvement was identified in 36% (10/28) of patients.
• HHV8-LANA1 positive lymphoid/plasmacytic cells in BMTB were indicative of bone marrow involvement.
• Bone marrow involvement was associated with lower CD4 and CD8 counts and frequently with hypercellularity and increased reticulin.

Conclusions:

• Bone marrow involvement is a significant feature in a substantial proportion of HHV8-MCD patients.
• HHV8-LANA1 immunohistochemistry is a valuable tool for diagnosing bone marrow infiltration in HHV8-MCD.
• Morphological features like lymphoid aggregates and marrow cellularity may correlate with disease presence.