HHV-6B found in 6% of chronic and recurrent lymphadenopathy cases

A group of Italian investigators have determined that a subset of patients with lymphadenopathy have active HHV-6B infections.

The study analyzed the clinical and pathological data of 486 HIV negative adult patients who underwent lymphadenectomy due to enlarged lymph nodes. Of these 486 patients, neoplastic disorders were documented in 299 cases (61.5%), and benign/reactive histopathological pathology was observed in 187 (38.5%) of cases. Of the benign cases, 111 (59.4%) demonstrated either reactive follicular hyperplasia (RFH) or paracortical expansion or combined features, and 7 (6.3%) demonstrated chronic and/or recurrent lymphadenopathy without constitutional symptoms.

In these 7 patients, the enlarged lymph nodes were round in shape, elastic, mobile, painless, insensitive to handling, and mimicked lymphoma upon ultrasonography examination. The well-defined etiology of reactive lymphadenopathy was ruled out.

The researchers performed immunohistochemical analysis of the lymph node tissues and found intense HHV-6B positive staining of follicular dendritic cells (FDCs) of germinal centers with scattered positivity of interfollicular cells in all 7 patients. Upon examination of serological markers, 4 patients were found to be positive for IgM, indicating an active infection, and the rest were positive for both HHV-6 IgG with high avidity and IgM. Five other patients were positive for only IgG with high avidity. This data suggests a viral reactivation rather than a primary infection.

The results of this study raise a number of possibilities that warrant further investigation to determine the relationship between HHV-6B reactivation and chronic and recurrent benign lymphadenopathy. The authors present the possibility that a local HHV-6B reactivation may indirectly modulate and trigger the proliferation of lymphocytes. However, they also raise the possibility that lymphadenopathy may trigger non-specific HHV-6B reactivation.

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