Discordant responses to progestin in a patient with uterine low-grade smooth-muscle tumors metastatic to the lung

A 58-year-old woman presented with pelvic, para-aortic masses and two isolated nodules in the right lung 6 years after hysterectomy and bilateral salpingo-oophorectomy for uterine leiomyoma. Laparotomy was carried out and all the intra-abdominal tumors were excised; pathology showed metastatic low-grade leiomyosarcomas. Immunohistochemical staining revealed a high expression level of estrogen and progesterone receptors in these tumors. The pulmonary nodules were left and the patient was given oral medroxyprogesterone acetate 200 mg daily after the operation. One of the pulmonary masses regressed progressively and had disappeared 7 months later on chest X-ray examination. However, the other was persistent. She then received wedge resection to excise the pulmonary nodule, which showed the same histologic pattern as the abdomen masses. However, the immunohistochemical staining on this nodule showed positive estrogen receptor expression but was negative for progesterone receptor expression. After the operation, she maintained progestin treatment and was tumor free for the following 12 months.