Histological features of kaposi sarcoma in a patient receiving highly active antiviral therapy

The introduction of highly active anti-retroviral therapy (HAART) has changed the clinical presentation of skin diseases in patients with the Acquired Immune Deficiency Syndrome (AIDS). This occurs as a consequence of a newly recognized effect of this therapy known as the "Immune Reconstitution Syndrome," which develops with improvement of immunity. One manifestation of this syndrome is alteration of the natural history of Kaposi sarcoma (KS). While there are multiple reports of KS regression during HAART, there is little documentation of the histologic changes that occur. We present the case of a 55-year-old homosexual male with KS for over 4 years who underwent 6 biopsies over a 3-year period before, during, and after HAART. Kaposi sarcoma lesions prior to HAART were multinodular with ill-defined borders clinically and demonstrated typical features of nodular stage KS histologically. After initiation of HAART in this patient, lesions became uninodular, well circumscribed, and histologically were noted to be less cellular and surrounded by a dense fibrotic stroma. Although the mechanisms for these histologic changes are not clear, it may be due to activity of HAART against human herpesvirus type 8 (HHV-8), the causative agent of KS, to reconstitution of immunity due to diminution in HIV viral load, or both.