Non-Hodgkin lymphomas concurrent with HHV8-associated Kaposi's sarcoma in the same lymph node in AIDS and non-AIDS patients.

Background: The association between lymphomas and Kaposi's sarcoma has been described since 1920. The simultaneous presence of the 2 pathologic entities within the same lymph node is a rare and interesting occurrence. In the few cases described, the presence of human herpesvirus 8 (HHV8) and Epstein-Barr virus (EBV) in the different neoplastic areas was investigated only by immunohistochemistry and in situ hybridization studies.

Methods: Two cases of concurrent non-Hodgkin lymphoma and Kaposi's sarcoma in the same lymph node are described: a diffuse large B cell lymphoma in an AIDS patient and a T cell-rich large B cell lymphoma in a HIV-negative patient, complete with the clinical, immunohistological and molecular features, the latter ones defined after isolation of the different neoplastic areas by laser capture microdissection.

Results: Polymerase chain reaction assays revealed HHV8 DNA sequences only in the microdissected Kaposi's sarcoma areas and EBV DNA sequences only in the lymphomatous areas in both cases, confirming the HHV8 infection only in the neoplastic sarcomatous cells and evidencing the EBV infection only in the lymphomatous cells.

Conclusion: This study represents a further confirmation of the supposed different etiopathogenic mechanisms of the 2 neoplasias, suggesting a coincidental occurrence even when localized in the same lymph node, independently from HIV infection.