XVI Harry Benjamin International Gender Dysphoria Association Symposium
17 - 21 August 1999, London

Reflections on "Transsexualism and Sex Reassignment" 1969 -1999

Short-Term and Long-Term Histologic Effects of Castration and Estrogen Treatment on Breast Tissue of Male-to-Female Transsexuals in Comparison with Chemically Castrated Males

Hage JJ, Kanhai RCJ, Karim RB, and van Diest PJ*

Departments of Plastic and Reconstructive Surgery, and Pathology*, Academisch Ziekenhuis Vrije Universiteit, Amsterdam, The Netherlands.

The histologic changes induced in the mammary gland of hormonally and surgically treated male-to-female transsexuals have, so far, not been reported on in the literature. We studied short-term and long-term histologic changes induced by chemical and surgical castration and estrogen therapy in the male-to-female transsexual breast, with particular reference to acinar and lobular formation. To objectify the influence of cross sex treatment, these histologic findings were compared to those observed in males treated hormonally for prostate cancer.

It is concluded that the slight increase of plasma estrogen-to-androgen ratio seen in idiopathic gynecomastia will usually not induce acinar and lobular formation in the male breast. In males treated with non-progestative anti-androgens for prostate cancer only moderate acinar and lobular formation occurs. Only in male-to-female transsexuals in whom progestative chemical castration is combined with feminizing estrogen therapy, will full acini and lobular formation occur. Hence, combined progestative anti-androgens and estrogens are necessary for the histology of the male breast to mimic the natural histology of the genetically female breast. Orchidectomy does not contribute to this.

Metaplasia may occur in breasts of male-to-female transsexuals but, so far, only 4 cases of breast cancer in male-to-female transsexuals have been documented. Provided male-to-female transsexuals are conservatively treated with estrogens, it is suggested that they run less lifetime risk of breast malignancy as do normal females because the mammagenesis is initiated later in life.