Background. The authors encountered six patients with Kaposi sarcoma in Okinawa; one was classic type, two were associated with adult T-cell leukemia (ATL), one was with multiple myeloma, and two were with acquired immune deficiency syndrome (AIDS). In the classic type, many nodular lesions were seen on the skin of the extremities and a few on the trunk, some of which were ulcerated. Most lesions regressed in 1.5 years. In four other patients (three without AIDS and one with AIDS), many plaques and a few nodular lesions were seen on the trunk, face, and extremities. The other patient with AIDS showed Kaposi sarcoma only in the lymph nodes and perineural tissues in the abdomen. Methods. Immunohistochemical and lectin histochemical studies were done on deparaffinized sections and on cells cultured from small pieces of tumor mass from the classic type Kaposi sarcoma. Isolation of viruses from tumor tissue was also attempted. Results. Large numbers of endothelial cells lining irregular vascular spaces, and some spindle cells showed positive reactions for Factor VIII-related antigen, Ulex europaeus 1 (UEA-1) (E.Y. Labs, Inc., San Mateo, CA), Griffonia simplicifolia (GS-1) (E.Y. Labs, Inc.) lectins, and epidermal growth factor (EGF) receptor antigen. Cytomegalovirus (CMV), hepatitis B, herpes simplex virus (HSV) 1 and 2, papillomavirus antigens, and human immunodeficiency virus (HIV) p24 core antigen were not seen in any patients, except in the patient with AIDS in whom CMV was demonstrated in tissues adjacent to the tumor (Patient 6). In cell culture, elongated spindle cells proliferated in plate and also in three-dimensional cultures. The cells were positive immunohistochemically for Factor VIII-related antigen and EGF receptor. They also stained lectin histochemically with UEA-1 and GS-1. Tube formations were demonstrated by electron microscopic study. Conclusions. Six cases of Kaposi sarcoma have been diagnosed within a short time span where this condition has previously been said to be rare. The studies suggest a vascular endothelial cell origin and growth factor regulated growth for this tumor.
