Fuzeon-induced collagenophagic granuloma: a peculiar granulomatous injection site reaction to Fuzeon--a case report and review of literature.

Enfuvirtide (ENF, T-20, or Fuzeon [Hoffman-La Roche Inc, Nutley, NJ, and Trimeris, Inc, Durham, NC]) is an HIV-1 fusion inhibitor and is the only injectable antiretroviral drug available. Injection site reactions (ISRs) are the most frequently reported adverse events, occurring in about 98% of patients. A granuloma annulare-like granulomatous ISR has been reported. We report a granulomatous ISR that is different from granuloma annulare and granuloma annulare-like reaction because it is rich in multinucleated giant cells engulfing altered collagen. We call this type of ISR a collagenophagic granuloma. Most previous reports-with the exception of 1 report-about ISRs with ENF treatment have used punch biopsies, which lack the depth to analyze the reticular dermis and subcutaneous tissue and, therefore, may have missed ISRs, which look like granuloma annulare, and the collagenophagic granulomatous reaction.