Topical treatment of cutaneous Kaposi sarcoma with imiquimod 5% in renal-transplant recipients: a clinicopathological observation

Kaposi sarcoma (KS) is a vascular neoplasm pathogenetically linked to human herpesvirus 8. Transplant recipients, in particular renal-transplant recipients (RTRs) are at higher risk for post-transplant (P)-KS which affects 0.211% of RTRs. The course of P-KS is influenced by the post-transplantation immunosuppressive treatment. Reduction of immunosuppressive drugs can result in tumour regression, and is the treatment of choice for P-KS, but is associated with the risk for transplant rejection. Imiquimod is a topically applied immunomodulator without relevant systemic absorption, and may thus represent a promising treatment for cutaneous KS in RTRs. The aim of this study was to investigate the clinical and histological effects of imiquimod in two RTRs with cutaneous KS. Imiquimod resulted in complete clinical and histologically proven remission in one patient, but in the second patient, although there was clinical remission, histological persistence of KS was found. Imiquimod may represent an effective treatment for RTRs with cutaneous P-KS. However, clinical remission does not necessarily indicate complete tumour regression, as shown in one of our patients, who had a persisting tumour, as shown by biopsy examination. Thus, histological confirmation is crucial to confirm complete response.