Presence of human herpesvirus-8 DNA sequences and overexpression of human IL-6 and cyclin D1 in inflammatory myofibroblastic tumor (inflammatory pseudotumor)

Inflammatory myofibroblastic tumor (IMT) is composed of myofibroblasts, pla sma cells, and lymphocytes. Cytokines are possibly involved in its pathogen esis. Human herpesvirus-8 (HHV-8) encodes cell cycle regulatory and signali ng proteins. A combination of nested PCR with several negative controls and Southern blot methods showed the presence of HHV-8 DNA in seven cases of I MT. Additionally, strong expression was demonstrated by in situ hybridizati on in many tumoral nuclei. Most of the myofibroblasts in all of the cases w ere immunoreactive for human IL-6 and cyclin D1. These cytokines probably h ave a paracrine action and may sustain myofibroblastic growth. HHV-8 could play an essential role in triggering IMT development by a local reactivatio n of Viral lytic replication. The relationship between HHV-8 and immunosupp ression status as the only associated cause for tumorigenesis should be rev ised.