Kaposi's sarcoma (KS) is a low-grade vascular tumor of mesenchymal origin which often affects mucocutaneous sites although it can manifest anywhere in the body. The pathogenesis of KS has been linked to human herpesvirus 8 (HHV-8) infection [1
]. Four distinct forms have been characterized including classic KS, endemic or African KS, organ transplant-associated KS and AIDS-related KS. HHV-8 has been found in all forms of KS [2
]. Classic KS typically occurs in older men of Mediterranean, Eastern European or Jewish origin. Endemic or African KS is prevalent in sub-Saharan Africa and is not associated with immune deficiency. Organ transplant-associated KS occurs after solid organ transplantation. AIDS-related KS preferentially affects homosexual or bisexual men compared with women, children, heterosexual drug users, or transfusion recipients [3
The exact mode of transmission of HHV-8 remains unclear. Suspected modes of transmission include saliva, sexual transmission, blood transfusions and solid organ transplantation [4
]. Seroprevalence depends on geography, with higher rates documented in Africa compared to North America and Northern Europe. HHV-8 infects a variety of cell types including lymphocytes, endothelial cells and keratinocytes which are thought to play a role in the pathogenesis of the disease. It has been speculated that circulating HHV-8-infected T cells may account for the multicentric nature of the lesions [1
]. Although HIV infection is not required for the development of KS, co-infection is linked with a higher incidence of the disease and a more aggressive clinical course.
AIDS-related KS was first described in 1981 and is the most common neoplasm associated with HIV infection [5
]. It is an AIDS-defining illness and occurs more frequently in patients with lower CD4 counts. Factors not associated with developing AIDS-related KS include the duration of HIV infection and patient age, unlike in classic KS where age is the main risk factor [6
]. AIDS-related KS frequently involves the skin, although extracutaneous spread is common and can also be seen in the absence of cutaneous disease. Cutaneous lesions most often arise on the lower extremities, face and genitalia. The lesions are typically papular but can also rarely be plaque-like and may occur in linear arrangements. Visually these lesions may appear red, purple, pink, or brown [7
]. Extracutaneous sites of disease include the oral cavity, gastrointestinal (GI) tract and respiratory tract, although any organ system may be involved. Disease of the GI tract is typically asymptomatic but can also lead to weight loss, nausea and vomiting, malabsorption, lower GI bleeding, obstruction, diarrhea and abdominal pain [8
]. The most common site of GI tract involvement is the small bowel, followed by the colon and stomach [9
]. Here we report the case of a patient with AIDS-related KS presenting with lower GI bleeding and anal pruritus.