Spontaneous regression of metastatic endometrial stromal sarcoma

Spontaneous regression of malignancy is rare and there appear to be no reports of spontaneous regression of endometrial stromal sarcoma. We report a rare case of metastatic endometrial stromal sarcoma that regressed spontaneously. A 58-year-old woman was admitted to hospital in January 1996 when her chest radiograph showed multiple nodular shadows in the left lower lung field. Computed tomography of the chest revealed bilateral nodules. Segmentectomy of the left lower lobe was performed by thoracoscopy. She had a past history of uterine myoma with metrorrhagia for which she had undergone a hystero-oophorectomy 10 years earlier. She also had a vaginal polyp removed 1 year earlier. The lung pathology was studied and the surgical specimens of the uterus and vagina were re-examined. The diagnosis was endometrial stromal sarcoma primarily arising in the uterus. The vaginal polyp and the pulmonary nodules were considered to be metastases. Samples of lung and vaginal tissues were positive for both estrogen and progesterone receptors. The patient was discharged without treatment in February 1996 and followed up in the outpatient clinic. The tumor shadow measuring 2 mm in diameter on admission was enlarged to 4 mm in diameter 1 year later. Surprisingly, spontaneous regression of the lung disease occurred at 33 months, the tumor size decreasing to 2 mm in diameter and to 1 mm at 46 months. No evidence of tumor enlargement was detected at the last follow-up in July 2001. Although the precise mechanism of tumor regression is unknown, metastatic endometrial stromal sarcoma may spontaneously regress.