AIDS-related complex, or ARC, was introduced after discovery of the HIV (Human Immunodeficiency Virus) when the medical community became aware of the inherent difficulties associated with treating patients suffering from an advanced case of HIV which gave rise to the term Acquired Immune Deficiency Syndrome (AIDS). The necessity for doctors to quickly and accurately understand the special needs of unknown patients suffering from AIDS in an emergency room situation was addressed with the creation of the term ARC.

ARC is "A prodromal phase of effects phase of infection with the human immunodeficiency virus ( HIV). Laboratory criteria separating AIDS-related complex ( ARC) from AIDS include elevated or hyperactive B-cell humoral immune responses, compared to depressed or normal antibody reactivity in AIDS; follicular or mixed hyperplasia in ARC lymph nodes, leading to lymphocyte degeneration and depletion more typical of AIDS; evolving succession of histopathological lesions such as localization of Kaposi's sarcoma

Kaposi's sarcoma

Kaposi's sarcoma is a tumor caused by Human herpesvirus 8 , also known as Kaposi's sarcoma-associated herpesvirus . It was originally described by Moritz Kaposi , a Hungarian dermatologist practicing at the University of Vienna in 1872. It became more widely known as one of the AIDS defining...

, signaling the transition to the AIDS.

Clinical use of this term was widely discontinued by the year 2000 in the United States after having been replaced by modern laboratory criteria.