Endometrial metastasis of a balloon cell melanoma mimicking a xanthomatousendometritis

zXanthomatous changes are unusual lesions of the corpus endometrium that ma y mask endometrial carcinoma. The term "xanthomatous endometritis" refers t o morphological changes frequently induced by estrogen stimulation. We repo rt for the first time a case of uterine metastasis of balloon-cell melanoma mimicking xanthomatous endometritis. Light microscopic, immunohistological ,and ultrastructural results are presented and discussed in connection with our ideas on the pathogenesis of this peculiar tumor. The findings favor t he hypothesis of a regressive phenomenon in the balloon-cell transformation of melanoma cells. The melan-A immunohistology seems to be more important in the diagnosis of balloon cell melanoma than the classic melanoma antibod y HMB 45.