Epithelioid Trophoblastic Tumor: Expanding the Clinicopathologic Spectrum of a Rare Malignancy.

Epithelioid trophoblastic tumor is a malignancy derived from the chorionic laeve-type intermediate trophoblast with sufficient rarity that the vast majority of literature on the topic exists in the form of case reports and small series. Classically, it is regarded as a well-circumscribed tumor with an expansile growth pattern that occurs in reproductive-aged women, usually after a normal pregnancy. However, we recently encountered a case of epithelioid trophoblastic tumor with aggressive spread throughout the abdomen and pelvis in a 68-yr-old female presenting 30 yr after her last delivery. Although to our knowledge this is the first report in a postmenopausal patient to be confirmed by molecular analysis of short tandem repeats, there are multiple similar case reports spanning a variety of clinical settings that deviate from the original description. We therefore sought to synthesize the clinicopathologic data among the available reports in the English literature, with emphasis on pathologic findings. While the overarching themes are largely unchanged, this series of 77 patients reveals a broader spectrum of disease and highlights frequent misdiagnosis. Here we present a clinicopathologic update on this rare entity, with emphasis on a practical approach to diagnosis.