MCD subclassification. (A) The traditional classification of MCD has been distinguished by HIV status. However, HHV-8 is responsible for cases of both HIV-positive and HIV-negative MCD. Therefore, HIV-based classification does not adequately distinguish the driving factor of MCD pathogenesis. (B) The newly proposed classification distinguishes MCD based on HHV-8-status, which is more accurate based on pathogenesis and response to treatments.