Background: The morphology of Kaposi's sarcoma is clinically and histologically the same in all clinical forms of the disease. However, there is a difference in the clinical and biological behaviour of the different forms of the disease. The behaviour also differs among individuals with the same form. The factors involved in the initiation and prognosis of the disease are still unknown. The classical form is more common in middle-aged Jews of East European or Mediterranean origin, people of Italian and southern Greek origin. Classic Kaposi's Sarcoma is seen relatively more frequently in Israel than in many other countries.

Objective: The aim of this study was to examine risk factors that influence the development and course of the disease.

Methods: This retrospective study includes 125 patients with Kaposi's sarcoma, all diagnosed and followed in the Department of Dermatology at Rambam Medical Center in Haifa.

Results: The group included 85 (68%) men and 40 (32%) women. Fourteen subjects received corticosteroid therapy and three were kidney transplant recipients. Age at onset of the disease was 21-87 years, with a mean age of 67. A total of 121 patients (96.8%) were Jews and four (3.2%) were non-Jews. A majority (61.6%) were of East European origin. The number of new cases each year was constant in relation to the general population, except for two peaks, one in 1970 and another in 1986-89. The lower limbs were involved in most patients. Extracutaneous involvement was present in 18.4%. Of all the subjects, 28 (22.4%) had diabetes mellitus and 21 (16.8%) had a second primary malignancy. The malignancies were of lymphoreticular origin in 10 patients, four in the urinary bladder, three had carcinoma of the large bowel and one of the pancreas.

Conclusion: Our study shows similar clinical findings to those described in other series. The relatively high frequency of carcinomas of the colon and urinary bladder was not reported elsewhere. We observed a consistent rate of new cases each year with two peaks in 1970 and 1986-1989, the cause of which deserves explanation. Of interest is the relative rise in the number of females with Kaposi's sarcoma. A relative high risk for developing Kaposi's sarcoma has been found among Jews of Ashkenazi origin compared to those of other ethnic groups. Israeli-born subjects presented a relatively more aggressive course of disease than others.