HHV-6 Positive Reed-Sternberg Cells in Nodular Sclerosis Hodgkin Lymphoma
Alexa J Siddon, David Hudnall. Yale School of Medicine, New Haven, CT
Background: Classical Hodgkin lymphoma is comprised of malignant Reed-Sternberg (RS) cells scattered within a mixed inflammatory background whose unusual bimodal age distribution suggests that infectious agent(s) may play a role in etiology. The presence of Epstein-Barr virus (EBV) within the RS cells in a proportion of cases supports this idea. However, most cases (>60%) of nodular sclerosis HL (NSHL) are EBV negative. HHV-6 is a near-ubiquitous virus that is first acquired in childhood and is typically followed by asymptomatic life-long persistence. We analyzed lymph nodes of patients with NSHL for both EBV and HHV-6, and sought to specifically localize viruses to the RS cells.
Design: Formalin-fixed paraffin-embedded lymph nodes from 20 cases of untreated NSHL were examined by EBER ISH, EBNA1 PCR, HHV-6 immunohistochemistry (IHC), and HHV-6 PCR as per protocol. In cases with HHV-6 positive RS cells by IHC, laser capture microdissection (LCM) was performed to collect purified RS cells. DNA from LCM-captured RS cells was extracted, amplified by whole genome amplication, and subjected to HHV-6 PCR to confirm that the RS cells were HHV-6 positive.
Results: Of the 20 cases of NSHL, 16 were HHV-6 PCR positive (80%). Seven cases (35%) contained numerous EBV positive RS cells while six cases (30%) contained numerous HHV-6 positive RS cells by IHC (in two of these six RS cells were positive for both HHV-6 and EBV). The presence of HHV-6 specifically within RS cells was confirmed by HHV-6 PCR on LCM-captured RS cells. PCR studies indicate that most of the HHV-6 positive cases harbor the HHV-6B strain. Preliminary molecular analysis suggests that the HHV-6 is truncated and likely integrated into the genome.
Conclusions: We have definitively demonstrated that HHV-6 genome is present within the neoplastic RS cells of a significant proportion of cases of NSHL while most cases were EBER ISH negative. These findings support that in some cases of NSHL, HHV-6 may play a role in etiology.
Wednesday, March 21, 2012 9:30 AM
Poster Session V # 202, Wednesday Morning