Histogenesis of Brenner tumors, I: histology and ultrastructure.

The histology of 36 benign and four proliferative Brenner tumors is reviewed, and the ultrastructural features of benign Brenner tumors are described. Evidence is presented for the origin of these tumors from celomic inclusion cysts through transitional metaplasia of the cyst lining and progressive growth of branching cords of transitional epithelium. Ovarian lesions associated with the Brenner tumor are described, particularly those containing mucinous epithelia, and their significance is discussed.