FDG-PET/CT findings, the vital clue to rare diagnosis of herpes simplex virus lymphadenitis simulating Richter transformation

Herpes simplex virus lymphadenitis is associated with tumor reduction in a chronic lymphocytic leukemia patient

BACKGROUND

Herpes simplex virus lymphadenitis (HSVL) is an unusual presentation of HSV reactivation in chronic lymphocytic leukemia (CLL) patients characterized by systemic symptoms and no herpetic lesions. The immune responses during HSVL have not been studied.

METHODS

Peripheral blood and lymph node samples of a patient with HSVL were obtained. HSV-2 viral load, antibody levels, B and T cell responses, cytokine levels, and tumor burden were measured.

RESULTS

This patient showed HSV-2 viremia for at least 6 weeks. During this period, she had a robust HSV-specific antibody response with neutralizing and antibody-dependent cellular phagocytosis activity. Activated (HLA-DR+, CD38+) CD4+ and CD8+ T cells increased 18-fold and HSV-specific CD8+ T cells were detected in the blood at higher numbers. HSV-specific B and T cell responses in the lymph node were also detected. Markedly elevated levels of pro-inflammatory cytokines in the blood were also observed. Surprisingly, a sustained decrease in CLL tumor burden without CLL-directed therapy was observed with this and also a prior episode of HSVL.

CONCLUSION

HSVL should be considered as part of the differential diagnosis in CLL patients who present with signs and symptoms of aggressive lymphoma transformation. An interesting finding was the sustained tumor control after 2 episodes of HSVL in this patient. This tumor burden reduction may be due to the HSV-specific response serving as an adjuvant for activating tumor-specific or bystander T cells. Studies in additional CLL patients are needed to confirm and extend these findings.

FUNDING

National Institutes of Health and Winship Cancer Institute.