Detection of pulmonary metastasis of low-grade endometrial stromal sarcoma 25 years after hysterectomy.

Endometrial stromal sarcoma (ESS) is a rare uterine sarcoma. Low-grade ESS occasionally recurs or metastasizes after long disease-free periods, a fact that may complicate the diagnosis. Here we report a case of multiple lung metastases in a 68-year-old woman who had been disease-free for 25 years after hysterectomy for a uterine tumor. Biopsy revealed that the tumor was composed of oval cells with slight nuclear atypism but without mitotic figures, suggesting a low-grade neoplasm. Immunostaining for intermediate filaments revealed strong positivity for vimentin and weak positivity for alpha-smooth muscle actin. In addition, immunostaining for estrogen and progesterone receptors, performed under suspicion of low-grade ESS, was positive. The uterine tumor resected many years before had shown a similar morphology. Thus, it was demonstrated that the lung neoplasm was a metastatic low-grade ESS that had appeared after many disease-free years. A review of the literature revealed that this case had the longest recorded interval between the occurrence of the initial ESS and the development of distant metastases. When low-grade sarcoma appears in the lungs of female patients, it is important to consider the possibility of low-grade ESS. Detailed information on the past clinical history, together with immunostaining for estrogen and progesterone receptors, are important diagnostic keys.