Tubuloreticular structures in Kaposi's sarcoma: a comparison of the classical and AIDS-associated forms.

The ultrastructural morphology of both the classical and the AIDS-associated forms of Kaposi's sarcoma was examined electron-microscopically. Tubuloreticular structures were found only in the AIDS-associated form of Kaposi's sarcoma, and not in the classical variant of the tumor. Moreover, the tubuloreticular structures, 20-30 nm in diameter, were present in very high numbers and in two different forms: the loosely intertwined tubuli, which were clearly predominant; and those forming a more compact pattern. These findings suggest that the presence of tubuloreticular structures may well be an ultrastructural marker for diagnosing AIDS and AIDS-associated disorders.