Primary squamous cell carcinoma with its spindle cell variant in the endometrium. A case report and review of literature

A case of squamous cell carcinoma of the endometrium in a 72-year-old woman is presented. A review of the previous 28 cases of endometrial squamous cell carcinoma (ESCC) that are adequately substantiated in the literature revealed several misconceptions about this rare tumor: the association with pyometra is not as frequent; the lesion does occur in premenopausal women; squamous metaplasia of the endometrium is not always coexistent; and malignant transformation of squamous metaplasia to ESCC has never been convincingly demonstrated. In the current case, a focal sarcomatoid spindle-cell tumor was associated with typical ESCC; however, light and electron microscopic examinations provided convincing evidence that the tumor was composed solely of ESCC. Ultrastructure of the spindle-cell tumor revealed it to be essentially identical to that of a spindle-cell variant of squamous cell carcinoma reported previously.