Endometrial stromal sarcoma: cytology of pulmonary metastasis including ultrastructural study.

An endometrial stromal sarcoma metastatic to the lung produced positive sputum cytology. A definitive characterization of the pulmonary lesion was made by ultrastructural study of cytologic material obtained by fine needle aspiration of the lung. The histologic grading and corresponding ultrastructural morphology of the endometrial stromal malignancy in relation to its propensity to spread to distant organs, such as the lung, are discussed.