Atypical endometriosis and other benigne diseases in a perimenopausal patient taking Tamoxifen for breast cancer

For woman taking tamoxifen, recent data strongly support the estrogen agonist role of tamoxifen as a causal factor for the increased risk of endometriosis, but also of leiomyomas, endometrial polyps, and endometrial hyperplasia. Case Report: A 54-year-old perimenopausal woman on tamoxifen (20mg/d), gravida 0, with a surgically treated invasive-lobular breast cancer with extensive carcinoma lobulare in situ (pT2 (m) pN0 (snl) pL0 G2 pTis (LCLIS) R0 M0 Ki–67 1%, ER+, PR+, Her–2 neu negative) was referred for evaluation of a pelvic mass. The ultrasonographic examination did show a regular endometrium, 1 uterine myoma (approx. 3 cm Ø), a right-sided sactosalpinx, ovarian cyst on the right resp. on the left-side without any criteria of malignancy. The CA 125 level was normal. With the exception of P, the endocrine status did show no signs of an ovarian insufficience. During laparoscopy a uterine subserous myoma, a right-sighted sactosalpinx, bilateral ovarian cysts, and a extended polypous, vascularized endometriosis of the bladder peritoneum, the pelvic wall and of the Douglas pouch were found. Complete pelvic deperitonealization, bilateral adnexectomy, but also the enucleation of the myoma was performed. The removed myoma did not show atypia or significant mitotic activity. The endometriotic lesions did present a strong expression of the Estrogen Receptor (ER), the Progesteron Receptor (PR), and the proliferation marker MIB–1. In addition, there was a strong (+++) CD34 expression, but no HER–2-neu expression. A switch to the aromatase inhibitor letrozol was recommended. Conclusion: The possibility of tamoxifen-induced or tamoxifen-driven endometriosis in peri- or postmenopausal patients with breast cancer should be considered.