Kaposi's sarcoma of internal organs. A multiparameter study of 86 cases

During the past decade, Kaposi's sarcoma (KS), one of the most common acquired immune deficiency syndrome-defining diseases, has been the subject of sustained research. However, basic questions about its etiology, histogenesis, growth, and dissemination remain unanswered. Even its nature, whether hyperplasia or neoplasia, is still controversial. Most studies and concepts to date have been based on dermatologic KS. The present study, in contrast, examines by various parameters a series of patients with KS of internal organs.

The series includes 86 cases (39 surgical specimens and 47 autopsies) of visceral and disseminated KS. The study is focused on the gross distribution of lesions, the mode of dissemination, the histologic patterns, and the cellular immunophenotypes, which are investigated with the use of 18 monoclonal antibodies.

The involvement of various organs, multiplicity of lesions, and progression of tumors were recorded. Seven histologic patterns forming a spectrum of cellular differentiation were distinguished. Immunophenotypes characteristic for different histologic patterns were recognized. Although some cell markers such as those recognized by antibodies against Factor VIII R-Ag, Actin, and Ulex europaeus were restricted to the well differentiated KS cells, others including CD34 and CD31 demonstrated a strong affinity for the entire spectrum of KS cell differentiation.

The present study of KS of internal organs revealed that poor grades of histologic and immunophenotypic differentiation correlated with invasion and dissemination, which are fundamental characteristics of malignant tumors.