Signet-ring cell carcinoma of the endometrium: a primary tumor masquerading as a metastasis.

Extragenital metastases to the endometrium are unusual, but several histologic features have been suggested as highly suggestive or even pathognomonic for this diagnosis. We report an endometrial carcinoma with a prominent signet-ring cell morphology and a diffusely permeative pattern of infiltration, features that have been reported as indicating an extragenital metastasis. To the best of our knowledge, this is the first reported case of a signet-ring cell carcinoma of the endometrium. Gynecological pathologists should be aware of this entity because of its potential primary of metastatic signet-ring carcinoma to be endometrium.