Diagnosis of gestational trophoblastic disease in early pregnancy

Abstract

Most pregnancies affected by complete or partial hydatidiform mole are now evacuated in early pregnancy. In the majority of cases, confident diagnosis is possible on the basis of morphological analysis of products of conception with routine haematoxylin and eosin stained sections. In early pregnancy however, the diagnostic criteria are subtly different from the classical pathological features, often still described in textbooks, which were derived from studies of molar tissue evacuated at later gestational age. In the first trimester, complete moles are characterized by moderate, patchy villus hydrops, prominent ‘budding’ of the villus outline, myxoid stromal degeneration with stromal karyorrhectic debris and collapsed blood vessels, scattered trophoblastic pseudoinclusions, and moderate trophoblast hyperplasia with pleomorphic extravillus trophoblast sheets. Partial moles demonstrate an irregular or ‘dentate’ villus outline with patchy mild-to-moderate hydrops, stromal blood vessels (collapsed or containing nucleated red blood cells), stromal fibrosis, mild focal villus trophoblast hyperplasia, scattered trophoblastic pseudoinclusions and often the presence of amnion or fetal tissue.