Distinct expression of Kaposi’s sarcoma‐associated herpesvirus‐encoded proteins in Kaposi’s sarcoma and multicentric Castleman’s disease

The expression of Kaposi’s sarcoma‐associated herpesvirus (KSHV/HHV‐8)‐encoded proteins is herein demonstrated in Kaposi’s sarcoma (KS) and multicentric Castleman’s disease (MCD) in a single lymph node derived from a patient with acquired immunodeficiency syndrome. Immunohistochemistry revealed that both lytic and latent KSHV proteins were expressed in cells of the MCD lesion. KSHV‐encoded viral interleukin‐6 was also detected in follicular dendritic cells of the germinal center. Cytoplasmic localization of open reading frame 59 protein and latency‐associated nuclear antigen suggested KSHV activation in the MCD lesion. Moreover, a high copy number of KSHV was detected in the blood. Clinically, pegylated‐liposomal doxorubicin induced regression of not only KS, but also lymphadenopathy of the MCD lesion with a decrease in KSHV load and human interleukin‐6 in the blood. To the best of the authors’ knowledge this is the first case demonstrating differential expression of virus proteins in two KSHV‐associated diseases, KS and MCD, in the same section. The case confirms lytic KSHV infection in MCD, and suggests that clinical symptoms of MCD might be closely linked with KSHV activation.