Classification of human ovarian tumors.

Most human ovarian tumors are classified into one of several categories based on presumed histogenesis and direction of differentiation. Separate categories are reserved for neoplasms composed of cells of several origins and for nonneoplastic disorders that simulate neoplasms. Using the World Health Organization Histologic Classification of Ovarian Tumors, histologic features for common and rare human ovarian tumors are described and illustrated.