The biopsy specimen revealed ectatic, bizarrely shaped vascular spaces that were incompletely lined with endothelial cells. In some areas, normal blood vessels protruded into newly formed vessels (the promontory sign). Erythrocytes were detected inside some of the spaces.
Kaposi sarcoma is an endothelial cell tumor that is believed to be caused by infection with human herpesvirus 8.1 Patients receiving immunomodulatory medication for various indications, such as organ transplantation, autoimmune diseases, or malignancies, are prone to develop KS.2- 4 This phenomenon is seen in as many as 3% to 6% of renal transplant recipients, with a mean period of 20 months of immunosuppressive therapy prior to the development of KS.5,6 Cyclosporine therapy carries a higher risk for development of KS than azathioprine and prednisone therapy.6 However, even the use of prednisone alone2,7 is related to an increased risk for development of KS.2 It is well documented that this type of KS responds well, and sometimes completely regresses, with reduction of dosage or deletion of 1 component of immunosuppressive therapy.3
Plaque on the Thigh of a Renal Transplant Recipient—Diagnosis. Arch Dermatol. 2003;139(3):381-386. doi:10.1001/archderm.139.3.381-a