This is a photograph of kaposi s sarcoma on the nose of a male patient Kaposi s sarcoma is a tumour made of the cells that normally form blood vessels There is strong evidence that a virus human herpesvirus 8 HHV 8 is the cause of kaposi s sarcoma There is a high incidence in patients with AIDS The lesions on the skin or in the mouth are often reddish blue or violet in light skinned people and may appear brown or black in dark skinned persons They may be flat or nodular Most of the time the lesions are not tender to the touch and do not cause significant pain