HHV-8 (KSHV) status and LANA-1 immunohistochemistry

What is measured: infection of tumour cells by human herpesvirus 8, and the amount of virus in blood. How: LANA-1 immunohistochemistry on tissue (a stippled nuclear pattern in the spindle cells of Kaposi sarcoma or the cells of primary effusion lymphoma, close to 100 percent sensitive and specific), quantitative PCR for KSHV DNA in blood (tracks KSHV inflammatory cytokine syndrome and multicentric Castleman disease activity better than Kaposi sarcoma burden), with limited use for serology. It is read with HIV status, CD4 count and viral load (the ACTG TIS staging of Kaposi sarcoma scores tumour, immune status and systemic illness) and with EBV testing, since effusion lymphoma is usually co-infected. What a result changes: it settles the diagnosis (Kaposi sarcoma against angiosarcoma and other vascular lesions, primary effusion lymphoma against other lymphomas, HHV-8-positive against idiopathic Castleman disease); starting or optimising antiretroviral therapy is the first treatment in HIV-associated Kaposi sarcoma, with liposomal doxorubicin, paclitaxel or pomalidomide for systemic disease; HHV-8 Castleman disease is treated with rituximab, with liposomal doxorubicin when severe; KICS needs rituximab and antivirals in intensive care; transplant-associated Kaposi sarcoma responds to reducing immunosuppression and switching to sirolimus. Where it matters: Kaposi sarcoma and HIV-associated lymphomas.